SIPPING J. Van Dyke Internet-Draft E. Burger, Ed. Expires: September 1, 2006 A. Spitzer Brooktrout Technology, Inc. February 28, 2006 Media Server Control Markup Language (MSCML) and Protocol draft-vandyke-mscml-07 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 1, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract Media Server Control Markup Language (MSCML) is a markup language used in conjunction with SIP to provide advanced conferencing and interactive voice response (IVR) functions. MSCML presents an application-level control model, as opposed to device-level control models. One use of this protocol is for communications between a conference focus and mixer in the IETF SIP Conferencing Framework. Van Dyke, et al. Expires September 1, 2006 [Page 1] Internet-Draft MSCML February 2006 Intellectual Property Rights Brooktrout Technology, Inc. is making their intellectual property right interest in MSCML available on a royalty-free basis, per the terms described in the online IETF list of claimed rights at http://www.ietf.org/ietf/IPR/SNOWSHORE-draft-vandyke-mscml.txt. Conventions used in this document RFC2119 [1] provides the interpretations for the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" found in this document. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. MSCML Approach . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Use of SIP Request Methods . . . . . . . . . . . . . . . . . . 5 4. MSCML Design . . . . . . . . . . . . . . . . . . . . . . . . . 7 4.1. Transaction Model . . . . . . . . . . . . . . . . . . . . 7 4.2. XML Usage . . . . . . . . . . . . . . . . . . . . . . . . 8 4.2.1. MSCML Time Values . . . . . . . . . . . . . . . . . . 9 5. Advanced Conferencing . . . . . . . . . . . . . . . . . . . . 9 5.1. Conference Model . . . . . . . . . . . . . . . . . . . . . 9 5.2. Configure Conference Request . . . 11 5.3. Configure Leg Request . . . . . . . . . . 13 5.4. Terminating a Conference . . . . . . . . . . . . . . . . . 14 5.5. Conference Manipulation . . . . . . . . . . . . . . . . . 15 5.6. Video Conferencing . . . . . . . . . . . . . . . . . . . . 17 5.7. Conference Events . . . . . . . . . . . . . . . . . . . . 17 5.8. Conferencing With Personalized Mixes . . . . . . . . . . . 18 5.8.1. MSCML Elements and Attributes for Personalized Mixes . . . . . . . . . . . . . . . . . . . . . . . . 19 5.8.2. Example Usage of Personalized Mixes . . . . . . . . . 20 6. Interactive Voice Response (IVR) . . . . . . . . . . . . . . . 25 6.1. Specifying Prompt Content . . . . . . . . . . . . . . . . 26 6.1.1. Use of the Prompt Element . . . . . . . . . . . . . . 26 6.2. Multimedia Processing for IVR . . . . . . . . . . . . . . 33 6.3. Playing Announcements . . . . . . . . . . . . . . . 34 6.4. Prompt and Collect . . . . . . . . . . . . . 36 6.4.1. Control of Digit Buffering and Barge-in . . . . . . . 36 6.4.2. Mapping DTMF Keys to Special Functions . . . . . . . . 37 6.4.3. Collection Timers . . . . . . . . . . . . . . . . . . 39 6.4.4. Logging Caller DTMF Input . . . . . . . . . . . . . . 42 6.4.5. Specifying DTMF Grammars . . . . . . . . . . . . . . . 42 6.4.6. Playcollect Response . . . . . . . . . . . . . . . . . 44 6.4.7. Playcollect Examples . . . . . . . . . . . . . . . . . 44 Van Dyke, et al. Expires September 1, 2006 [Page 2] Internet-Draft MSCML February 2006 6.5. Prompt and Record . . . . . . . . . . . . . . 46 6.5.1. Prompt Phase . . . . . . . . . . . . . . . . . . . . . 46 6.5.2. Record Phase . . . . . . . . . . . . . . . . . . . . . 48 6.5.3. Playrecord Response . . . . . . . . . . . . . . . . . 50 6.5.4. Playrecord Examples . . . . . . . . . . . . . . . . . 50 6.6. Stop Request . . . . . . . . . . . . . . . . . . . 51 7. Call Leg Events . . . . . . . . . . . . . . . . . . . . . . . 52 7.1. Keypress Events . . . . . . . . . . . . . . . . . . . . . 53 7.1.1. Keypress Subscription Examples . . . . . . . . . . . . 55 7.1.2. Keypress Notification Examples . . . . . . . . . . . . 57 7.2. Signal Events . . . . . . . . . . . . . . . . . . . . . . 59 7.2.1. Signal Event Examples . . . . . . . . . . . . . . . . 60 8. Managing Content . . . . . . . . . . . . . . . 62 8.1. Managecontent Attributes . . . . . . . . . . . . . . . . . 62 8.2. Managecontent Example . . . . . . . . . . . . . . . . . . 64 9. Fax Processing . . . . . . . . . . . . . . . . . . . . . . . . 65 9.1. Recording a Fax . . . . . . . . . . . . . . . 65 9.2. Sending a Fax . . . . . . . . . . . . . . . . . 68 10. MSCML Response Attributes and Elements . . . . . . . . . . . . 70 10.1. Mechanism . . . . . . . . . . . . . . . . . . . . . . . . 70 10.2. Base Attributes . . . . . . . . . . . . . . . . 70 10.3. Response Attributes and Elements for . . . 71 10.4. Response Attributes and Elements for . . . . . . . 72 10.4.1. Reporting Content Retrieval Errors . . . . . . . . . . 73 10.5. Response Attributes and Elements for . . . . 74 10.6. Response Attributes and Elements for . . . . 75 10.7. Response Attributes and Elements for . . . 77 10.8. Response Attributes and Elements for and . . . . . . . . . . . . . . . . . . . . . . . 77 11. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 79 11.1. Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 79 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 90 12.1. IANA Registration of MIME media type application/mediaservercontrol+xml . . . . . . . . . . . . 90 13. Security Considerations . . . . . . . . . . . . . . . . . . . 91 14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 92 14.1. Normative References . . . . . . . . . . . . . . . . . . . 92 14.2. Informative References . . . . . . . . . . . . . . . . . . 93 Appendix A. Regex Grammar Syntax . . . . . . . . . . . . . . . . 94 Appendix B. Contributors . . . . . . . . . . . . . . . . . . . . 95 Appendix C. Acknowledgements . . . . . . . . . . . . . . . . . . 96 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 97 Intellectual Property and Copyright Statements . . . . . . . . . . 98 Van Dyke, et al. Expires September 1, 2006 [Page 3] Internet-Draft MSCML February 2006 1. Introduction This document describes the Media Server Control Markup Language (MSCML) and its usage. It describes payloads that one can send to a Media Server using standard SIP INVITE and INFO methods and the capabilities these payloads implement. RFC 4240 [2] describes Media Server SIP URI formats. Prior to MSCML, there was not a standard way to deliver SIP-based enhanced conferencing. Basic SIP constructs, such as described in RFC 4240 [2], serves simple n-way conferencing well. The SIP URI provides a natural mechanism for identifying a specific SIP conference, while INVITE and BYE methods elegantly implement conference join and leave semantics. However, enhanced conferencing applications also require features such as sizing and resizing, in- conference IVR operations (e.g., recording and playing participant names to the full conference) and conference event reporting. MSCML payloads within standard SIP methods realize these features. The structure and approach of MSCML satisfy the requirements set out in conferencing-framework [10]. In particular, MSCML serves as the interface between the conference factory and a centralized conference mixer. In this case, a media server has the role of the conference mixer. There are two broad classes of MSCML functionality. The first class includes primitives for advanced conferencing such as conference configuration, participant leg manipulation, and conference event reporting. The second class comprises primitives for interactive voice response (IVR). These include collecting DTMF digits and playing and recording multimedia content. MSCML fills the need for IVR and conference control with requests and responses over a SIP transport. VoiceXML [11] fills the need for IVR with requests and responses over a HTTP transport. This enables developers to use whatever model fits their needs best. In general, a Media Server offers services to SIP UAC's such as Application Servers, Feature Servers, and Media Gateway Controllers. See the IPCC Reference Architecture [12] for definitions of these terms. It is unlikely, but not prohibited, for end user SIP UAC's to have a direct signaling relationship with a media server. The term "client" is used in this document to generically refer to an entity that interacts with the Media Server using SIP and MSCML. The Media Server fulfills the role of the Media Resource Function (MRF) in the IP Multimedia Subsystem (IMS) [13] as described by 3GPP. MSCML and RFC 4240 [2], upon which MSCML builds, are specifically Van Dyke, et al. Expires September 1, 2006 [Page 4] Internet-Draft MSCML February 2006 focused on the Mr interface which supports interactions between application logic and the MRF. This document describes a working framework and protocol with which there is considerable implementation experience. Application developers and service providers have created several MSCML-based services since the availability of the initial version in 2001. This experience is highly relevant to the ongoing work of the IETF, particularly the SIP [24], SIPPING [25], MMUSIC [26], and XCON [27] work groups, the IMS [28] work in 3GPP and the CCXML work in the Voice Browser Work Group of the W3C. 2. MSCML Approach It is critically important to emphasize that the goal of MSCML is to provide an application interface that follows the SIP, HTTP, and XML development paradigm to foster easier and more rapid application deployment. This goal is reflected in MSCML in two ways. First, the programming model is that of peer to peer rather than master-slave. Importantly, this allows the media server to be used simultaneously for multiple applications rather than being tied to a single point of control. It also enables standard SIP mechanisms to be used for media server location and load-balancing. Second, MSCML defines constructs and primitives that are meaningful at the application level to ensure that programmers are not distracted by unnecessary complexity. For example, the mixing resource operates on constructs such as conferences and call participants rather than directly on individual media streams. The MSCML paradigm is important to the developer community, in that developers and operators conceptually write applications about calls, conferences, and call legs. For the majority of developers and applications this approach significantly simplifies and speeds development. 3. Use of SIP Request Methods As mentioned above, MSCML payloads may be carried in either SIP INVITE or INFO requests. The initial INVITE, which creates an enhanced conference, MAY include an MSCML payload. A subsequent INVITE to the same Request-URI joins a participant leg to the conference. This INVITE MAY include an MSCML payload. The initial INVITE which establishes an IVR session MUST not include an MSCML payload. The client sends all mid-call MSCML payloads for Van Dyke, et al. Expires September 1, 2006 [Page 5] Internet-Draft MSCML February 2006 conferencing and IVR via SIP INFO requests. The media server transports MSCML responses in the final response to the SIP INVITE containing the matching MSCML request or in a SIP INFO message. The only allowable final response to a SIP INFO containing a message body is a 200 OK, per RFC 2976 [3]. Therefore, if the client sends the MSCML request via SIP INFO, the media server responds with the MSCML response in a separate INFO request. In general, these responses are asynchronous in nature and require a separate transaction due to timing considerations. There has been considerable debate on the use of the SIP INFO method for any purpose. Our experience is that MSCML would not have been possible without it. At the time the first MSCML specification was published, the first SIP Event Notification draft had just been submitted as an individual submission. At that time, there was no mechanism to link SUBSCRIBE/NOTIFY to an existing dialog. This prevented its use in MSCML since all events occurred in an INVITE established dialog. And while SUBSCRIBE/NOTIFY was well suited for reporting conference events its semantics seemed inappropriate for modifying a participant leg or conference setting where the only "event" was the success or failure of the request. Lastly, since SIP INFO was an established RFC, most SIP stack implementations supported it at that time. We had few if any interoperability issues as a result. As it turns out, using NOTIFY is not appropriate, as the NOTIFY would be in response to an implicit subscription. The SIP and SIPPING lists have discussed the dangers of implicit subscription. Using SUBSCRIBE is not appropriate for two reasons. The first is semantic. The purpose of SUBSCRIBE is to register interest in User Agent state. However, using SUBSCRIBE for MSCML results in the SUBSCRIBE modifying the User Agent state. The second reason SUBSCRIBE is not appropriate is because MSCML is inherently call- based. The association of a SIP dialog with a call leg means MSCML can be incredibly straightforward. For example, if one used SUBSCRIBE or other SIP method to send commands about some context, one must identify that context somehow. Relating commands to the SIP dialog they arrive on defines the context for free. Moreover, it is conceptually easy for the developer. In order to guarantee interoperability with this specification, as well as with SIP User Agents that are unaware of MSCML, SIP UACs that wish to use MSCML services MUST specify a service indicator which supports MSCML in the initial INVITE. RFC 4240 [2] defines the service indicator "conf" which MUST be used for MSCML conferencing applications. The service indicator "ivr" MUST be used for MSCML Van Dyke, et al. Expires September 1, 2006 [Page 6] Internet-Draft MSCML February 2006 applications that do not require mixing services. The media server MUST support moving the call between services through sending the media server a BYE on the existing dialog and establishing a new dialog with an INVITE to the desired service. Media servers SHOULD support moving between services without requiring modification of the previously established SDP parameters. This is achieved by sending a re-INVITE on the existing dialog with the Request-URI modified to specify the new service desired by the client. This eliminates the need for the client to send an INVITE to the caller or gateway to establish new SDP parameters. The media server, as a SIP UAS, MUST respond appropriately to an INVITE which contains an MSCML body. If MSCML is not supported the media server MUST generate a 415 final response and include a list of the supported content types in the response per RFC 3261 [4]. The media server MUST also advertise its support of MSCML in responses to OPTIONS requests, by including "application/mediaservercontrol+xml" as a supported content type in an Accept header. This alleviates the major issues with using INFO for the transport of application data, namely the User Agent's proper interpretation of what is, by design, an opaque message request. 4. MSCML Design 4.1. Transaction Model To avoid undue complexity MSCML establishes two rules regarding MSCML usage. The first is that only one MSCML body may be present in a SIP request. The second is that each MSCML body may contain only one request or response. This greatly simplifies transaction management. MSCML syntax does provide for the unique identification of multiple requests in a single body part. However, this is not supported in this specification. Per the guidelines of RFC 3470 [14], MSCML bodies MUST be well formed and valid. MSCML is a direct request-response protocol. There are no provisional responses, only final responses. A request may, however, result in multiple notifications. For example, a request for active talker reports will result in a notification for each speaker set. This maps to the three major element trees for MSCML: , , and . Figure 1 shows a request body. Depending on the command, one can send the request in an INVITE or an INFO. Figure 2 shows a response Van Dyke, et al. Expires September 1, 2006 [Page 7] Internet-Draft MSCML February 2006 body. The SIP INFO method transports response bodies. Figure 3 shows a notification body. The SIP INFO method transports notifications. ... request body ... Figure 1: MSCML Request Format ... request body ... Figure 2: MSCML Response Format ... notification body ... Figure 3: MSCML Notification Format MSCML requests MAY include a client defined ID attribute for the purposes of matching requests and responses. The values used for these IDs need only be unique within the scope of the dialog in which the requests are issued. 4.2. XML Usage In the philosophy of XML as a text-based description language, and not a programming language, MSCML makes the choice of many attribute values for readability by a human. Thus many attributes that would often be "boolean" instead take "yes" or "no" values. For example, what does 'report="false"' or 'report="1"' mean? However, 'report="yes"' is clearer: I want a report. Some programmers prefer the precision of a boolean. To satisfy both styles, MSCML defines an XML type, "yesnoType", that takes on the values "yes" and "no" as Van Dyke, et al. Expires September 1, 2006 [Page 8] Internet-Draft MSCML February 2006 well as "true", "false", "1", and "0". Many attributes in the MSCML schema have default values. In order to limit demands on the XML parser, MSCML applies these values at the protocol, not XML, level. The MSCML schema documents these defaults as XML annotations to the appropriate attribute. 4.2.1. MSCML Time Values For clarity, time values in MSCML are based on the time designations described in Cascading Style Sheets, level 2 (CSS2) Specification [15]. Their format consists of a number immediately followed by an optional time unit identifier of the form: ms: milliseconds (default) s: seconds If no time unit identifier is present the value MUST be interpreted to be in milliseconds. As extensions to [15] MSCML allows the string values "immediate" and "infinite" which have special meaning for certain timers. 5. Advanced Conferencing 5.1. Conference Model The advanced conferencing model is a star controller model, with both signaling and media directed to a central location. Figure 4 depicts a typical signaling relationship between end users' UAC's, a conference application server, and a media server. The document cc-conferencing [10] makes use of this model. The application server is an instantiation of the conference focus. The Media Server is an instantiation of the media mixer. Note that user- level constructs, such as event notifications, are in the purview of the application server. This is why, for example, the Media Server sends active talker reports using MSCML notifications, while the application server would instead use the conference package [16] for individual notifications to SIP user agents. Note that we do not recommend the use of the conference package for media server to application server notifications because none of the filtering and membership information is available at the media server. Van Dyke, et al. Expires September 1, 2006 [Page 9] Internet-Draft MSCML February 2006 +-------+ | UAC 1 |---\ Public URI +-------------+ +-------+ \ _____________| Application | / / | Server | Not shown: +-------+ / / +-------------+ RTP flows directly | UAC 2 |---/ / | Private between UAC's and +-------+ / | URI Media Server . / +--------------+ : / | | +-------+ / | Media Server | | UAC n |---/ | | +-------+ +--------------+ Figure 4: Conference Model Each UAC sends an INVITE to a Public Conference URI. Presumably, the client publishes this URI, or it is an ad hoc URI. In any event, the client generates a Private URI, following the rules specified by RFC 4240 [2]. That is, the URI is of the form: sip:conf=UniqueID@ms.example.net Where UniqueID is a unique conference identifier and ms.example.net is the host name or IP address of the media server. There is nothing to prevent the UAC's from contacting the media server directly. However, one would expect the owner of the media server to restrict who can use its resources. As for basic conferencing, described by RFC 4240 [2], the first INVITE to the media server with a UniqueID creates a conference. However, in advanced conferencing, the first INVITE MAY include a MSCML payload rather than the SDP of a conference participant. The payload conveys extended session parameters (e.g., number of participants) that SDP does not readily express but the media server must know to allocate the appropriate resources. When the conference is created by sending an INVITE containing a MSCML payload the resulting SIP dialog is termed the "Conference Control Leg." This leg has several useful properties. The lifetime of the conference is the same as that of its control leg. This ensures that the conference remains in existence even if all participant legs leave or have not yet arrived. In addition, when the client terminates the Conference Control Leg the Media Server automatically terminates all participant legs. The Conference Control Leg is also used for for play or record operations to/from the entire conference and for active talker notifications. Full conference media operations and active talker report subscriptions MUST be performed on the Conference Control Leg. Van Dyke, et al. Expires September 1, 2006 [Page 10] Internet-Draft MSCML February 2006 Creation of a Conference Control Leg is RECOMMENDED because full advanced conferencing capabilities are not available without it. Clients MUST establish the Conference Control Leg in the initial INVITE that creates the conference; it cannot be created later. Once the client has created the conference with or without the Conference Control Leg, participants can be joined to the conference. This is achieved by the client directing an INVITE to the Private Conference URI for each participant. Using the example conference URI given above, this would be sip:conf=UniqueID@ms.example.net . 5.2. Configure Conference Request The request has two attributes that control the resources the Media Server sets aside for the conference. These attributes are described in Table 1. NOTE: In the attribute tables the column labeled "R/O" indicates whether the attribute is required (R) or optional (O). If the attribute is only required under certain conditions the value (O*) is placed in the column. In that case there will be a note in the description preceded by an asterisk that explains the cases where it is required. +------------------+---------+-----+--------------------------------+ | Attribute | Default | R/O | Description | +------------------+---------+-----+--------------------------------+ | reservedtalkers | | O* | The maximum number of talker | | | | | legs allocated for the | | | | | conference. *Required when | | | | | establishing the Conference | | | | | Control Leg but optional in | | | | | subsequent | | | | | | | | | | requests. | | reserveconfmedia | yes | O | Controls allocation of | | | | | resources to enable playing or | | | | | recording to or from the | | | | | entire conference | +------------------+---------+-----+--------------------------------+ Table 1: Conference Attributes When the reservedtalkers+1st INVITE arrives at the media server, the media server MUST generate a 486 Busy Here response. NOTE: It would be symmetric to have a reservedlisteners parameter. However, the practical limitation on the Media Server is the number of talkers for a mixer to monitor. In either case, the Van Dyke, et al. Expires September 1, 2006 [Page 11] Internet-Draft MSCML February 2006 client regulates who gets in to the conference by either proxying the INVITEs from the user agent clients or metering to whom it gives the conference URI. For example, to create a conference with up to 120 active talkers and the ability to play audio into the conference or record portions or all of the conference full mix, the application server specifies both attributes, as shown in Figure 6. Figure 6: 120 Speaker MSCML Example Figure 7 shows a conference with up to five active speakers without the capability to play or record audio into the conference. Figure 7: 5 Speaker MSCML Example In addition to these attributes a request MAY contain a child element. The element is used to request notifications for conference wide active talker events. Detailed information regarding active talker events is contained in Section 5.7. The client MUST include a request in the initial INVITE which establishes the conference when creating the Conference Control Leg. The client server MUST issue asynchronous commands, such as , separately (i.e., in INFO messages) to avoid ambiguous responses. Media operations on the Conference Control leg are performed internally, with no need for external RTP streams. Accordingly, the Media Server does not expect RTP on the Conference Control Leg. Therefore, the client MUST send either no SDP or hold SDP in the INVITE request containing a payload. The Van Dyke, et al. Expires September 1, 2006 [Page 12] Internet-Draft MSCML February 2006 Media Server MUST treat SDP with all media lines set to "inactive" or with connection addresses set to 0.0.0.0 (for backwards compatibility) as hold SDP. The Media Server sends a response when it has finished processing the request. The format of the response is detailed in Section 10.2. 5.3. Configure Leg Request Conference legs have a number of properties the client server can modify. These are set using the request. This request has the attributes and defaults shown in Table 2. +-----------+---------+-----+---------------------------------------+ | Attribute | Default | R/O | Description | +-----------+---------+-----+---------------------------------------+ | type | talker | O | Consider this leg's audio for | | | | | inclusion in the output mix. | | | | | Alternative is "listener". | | dtmfclamp | yes | O | Remove detected DTMF digit from the | | | | | input audio. | | toneclamp | yes | O | Remove tones from the input audio. | | | | | Tones include call progress tones and | | | | | the like. | | mixmode | full | O | Be a candidate for the full mix. | | | | | Alternatives are "mute" to not allow | | | | | audio in the mix, "parked" to remove | | | | | any media streams from the leg, | | | | | "preferred" to give this stream | | | | | preferential selection in the mix | | | | | (i.e., even if not loudest talker, | | | | | include media, if present, from this | | | | | leg in the mix) and "private" which | | | | | enables personalized mixes. | +-----------+---------+-----+---------------------------------------+ Table 2: Conference Leg Attributes In addition to these attributes, there are four child elements defined for . These are , , and . The first two, and , modify the gain applied to the input and output audio streams respectively. These may contain , to use automatic gain control (AGC) or . The element has the attributes "startlevel", "targetlevel", and "silencethreshold". All of the parameters are in dB. The Van Dyke, et al. Expires September 1, 2006 [Page 13] Internet-Draft MSCML February 2006 element has the attribute "level", which is in dB. The default for both and is . The Media Server MAY silently cap or ignore or requests which exceed the gain limits imposed by the platform. The element is used to create and manipulate groups for personalized mixes. Details of personalized mixes are discussed in Section 5.8. The element is used to request notifications for call leg related events such as asynchronous DTMF digit reports. Detailed information regarding call leg events is discussed in Section 7. If the default parameters are acceptable for the leg the client wishes to enter into the conference, then a normal SIP INVITE, with no MSCML body, is sufficient. However, if the client wishes to modify one or more of the parameters, the client can include a MSCML body in addition to the SDP body. The client can modify the conference leg parameters during the conference by issuing a SIP INFO on the dialog representing the conference leg. Of course, the client cannot modify SDP in an INFO message. The Media Server sends a response when it has finished processing the request. The format of the response is detailed in Section 10.3. 5.4. Terminating a Conference To remove a leg from the conference, the client issues a SIP BYE request on the selected dialog representing the conference leg. The client can terminate all legs in a conference by issuing a SIP BYE request on the Conference Control Leg. If one or more participants are still in the conference when the media server receives a SIP BYE request on the Conference Control Leg, the media server issues SIP BYE requests on all of the remaining conference legs to ensure clean up of the legs. The media server returns a 200 OK to the SIP BYE request as it sends BYE requests to the other legs. This is because we cannot issue a provisional response to a non-INVITE request, yet the teardown of the other legs may exceed the retransmission timer limits of the original request. While the conference is being cleaned up the Media Server MUST reject any new INVITEs to the terminated conference with a 486 Busy Here response. This response indicates that the specified conference cannot accept new participants. Van Dyke, et al. Expires September 1, 2006 [Page 14] Internet-Draft MSCML February 2006 5.5. Conference Manipulation Once the conference has begun, the client can manipulate the conference as a whole or a particular participant leg by issuing commands on the associated SIP dialog. For example, by sending MSCML requests on the Conference Control Leg the client can request the media server to record the conference, play a prompt to the conference or request reports on active talker events. Similarly, the client may mute a participant leg, configure a personalized mix or request reports for call leg events such as DTMF keypresses. Figure 8 and Figure 9 show two sample commands. The first plays a prompt into the conference. The second records the entire conference to the URL specified by the 'recurl' attribute. This "file://" URL scheme happens to do the write over NFS, per configuration at the media server. NOTE: The provisioning of NFS mount points and their mapping to the "file://" schema is purely a local matter at the media server. Figure 8: Full Conference Audio Command - Play Figure 9: Full Conference Audio Command - Record The response to this last request will be similar to the one shown in Figure 10. Van Dyke, et al. Expires September 1, 2006 [Page 15] Internet-Draft MSCML February 2006 Figure 10: Sample Change Command Response A client can modify a leg by issuing an INFO on the dialog associated with the participant leg. For example, Figure 11 mutes a conference leg. Figure 11: Sample Change Leg Command In Figure 8, we saw a request to play a prompt to the entire conference. The client can also request to play a prompt to an individual call leg. In that case, the MSCML request is issued within the SIP dialog of the desired conference participant. Section 6 describes the interactive voice response (IVR) services offered by MSCML. If an IVR command arrives on the control channel, it takes effect on the whole conference. This is a mechanism for playing prompts to the entire conference (e.g., announcing new participants). If an IVR command arrives on an individual leg, it only affects that leg. This is a mechanism for interacting with users, such as the creation of "waiting rooms", allowing a user to mute themselves using key presses, allowing a moderator to out-dial, etc. A participant leg MUST be configured with mixmode="parked" prior to the issuance of any IVR commands with prompt content ('prompturl' attribute or element). Parking the leg isolates the participant's input and output media from the conference and allows use of those streams for playing and recording purposes. However, the mixmode has no effect if just digit collection or recording is desired. and requests without prompt content MAY be sent on participant legs without setting mixmode="parked". Van Dyke, et al. Expires September 1, 2006 [Page 16] Internet-Draft MSCML February 2006 5.6. Video Conferencing MSCML controlled advanced conferences as well as RFC 4240 [2] controlled basic conferences implicitly support video conferencing in the form of video switching. In video switching the video stream of the loudest talker (with some hysteresis) is sent to all participants other than that talker. The loudest talker receives the video stream from the immediately prior loudest talker. Media Servers MUST ensure that participants receive video media compatible with their session. For example, a participant who has established an H.263 video stream will not receive video from another participant employing H.264 media. Media Servers SHOULD implement video transcoding to minimize media incompatibilities between participants. The Media Server MUST switch video streams only when it receives a refresh video frame. A refresh frame contains all of the video information required to decode that frame (i.e. there is no dependency on data from previous video frames). Refresh frames are large and generally sent infrequently to conserve network bandwidth. The Media Server MUST implement standard mechanisms to request that the new loudest talker's video encoder transmits a refresh frame to ensure video can be switched quickly. 5.7. Conference Events A client can subscribe for periodic active talker event reports which indicate which participants are included in the conference mix. As these are conference level events the subscription and notifications are sent on the Conference Control Leg. Media Servers MAY impose limits on the minimum interval for active talker reports for performance reasons. If the client request is below the imposed minimum the Media Server SHOULD set the interval to the minimum value supported. To limit unnecessary notification traffic the Media Server SHOULD NOT send a report if the active talker information for the conference has not changed during the reporting interval. A request for an active talker report is in Figure 12. The active talker report enumerates the current call legs in the mix. Van Dyke, et al. Expires September 1, 2006 [Page 17] Internet-Draft MSCML February 2006 Figure 12: Active Talker Request Event notifications are sent in SIP INFO messages. Figure 13 shows an example report. Figure 13: Active Talker Event Example The value of the "callid" attribute in the element corresponds to the value of the SIP Call-ID header of the associated dialog. This enables the client to associate the active talker with a specific participant leg. 5.8. Conferencing With Personalized Mixes MSCML enables clients to create personalized mixes through the element for scenarios where the standard mixmode settings do not provide sufficient control. The element is a child of . To create personalized mixes the client has to identify the relationships among the participants. This is accomplished by manipulating two MSCML objects. These objects are: Van Dyke, et al. Expires September 1, 2006 [Page 18] Internet-Draft MSCML February 2006 o The list of team members ( elements) set using o The mixmode attribute set through The media server uses the values of these objects to determine which audio inputs to combine for output to the participant. In a normal conference, each participant hears the conference mix minus their own input if they are part of the mixed output. The team list enables the client to specify other participants that the leg can hear in addition to the normal mixed output. Note that personalized mix settings apply only to audio media and do not affect video switching. Team relationships are implicitly symmetric. If the client sets participant A as a team member of participant B, then the media server automatically sets participant B as a team member for A. The id attribute set through is used to identify the various participants. A unique ID MUST be assigned to each participant included in a personalized mix. The ID's used MUST be unique within the scope of the conference in which they appear. By itself, the team list only defines those participants that the leg can hear. The mixmode attribute of each team member determines whether to include their audio input in the personalized mix. If the client sets the teammate's mixmode to private, then it is part of the mix. If the mixmode is set to any other value, it is not. 5.8.1. MSCML Elements and Attributes for Personalized Mixes Control of personalized mixes rely on two major MSCML elements. o using the mixmode attribute, mixmode="private" o The element allows the user to make the participants members of a team within a specific conference. It is a child of the parent element. The client sends the element in a request in either a SIP INVITE or SIP INFO. o In an INVITE to join a participant whose properties differ from the properties established for the conference as a whole. o In an INFO to change the properties for an existing leg. The two attributes of the configure_team element are "id" and "action". The id attribute MUST contain the unique ID of the leg being modified, as set in the original request. The action attribute can take on the values "add", "delete", "query", and "set". The default value is "query". This attribute allows the user Van Dyke, et al. Expires September 1, 2006 [Page 19] Internet-Draft MSCML February 2006 to modify the team list. Table 3 describes the actions that can be performed on the team list. +--------+----------------------------------------------------------+ | Action | Description | +--------+----------------------------------------------------------+ | add | Adds a teammate to the mix. | | delete | Deletes a teammate from the mix. | | query | Returns the teammate list to the requestor. This is the | | | default value. | | set | Creates a team list when followed by | | | and also removes all the teammates from the team list | | | for example, when the creator (originator) of the team | | | list on that specific conference leg wants to remove all | | | of the teammates from the team. If the set operation | | | removes all teammates from a participant, that | | | participant hears the full conference mix. | +--------+----------------------------------------------------------+ Table 3: Configure Team Actions 5.8.2. Example Usage of Personalized Mixes A common use of personalized mixing is to support coaching of one participant by another. The coaching scenario includes three participants: o Coach (supervisor) who coaches the agent o Agent who interacts with the client o Client (customer) who receives advice from the agent Table 4 illustrates the details of the coached conference topology. +-------------+------------+------------+---------+-----------------+ | Participant | ID | Team | Mixmode | Hears | | | | Members | | | +-------------+------------+------------+---------+-----------------+ | Supervisor | supervisor | Agent | Private | customer + | | | | | | agent | | Agent | agent | Supervisor | Full | customer + | | | | | | supervisor | | Customer | customer | none | Full | agent | +-------------+------------+------------+---------+-----------------+ Table 4: Coached Conference Example To create this topology, the client performs the followng actions: Van Dyke, et al. Expires September 1, 2006 [Page 20] Internet-Draft MSCML February 2006 1. Join each leg to the conference, being certain to include a unique ID in the request. The leg ID needs to be unique only within the scope of the conference to which it belongs. 2. Configure the teammate list and mixmode of each participant as required. Both actions (step 1 and 2) may be combined in a single MSCML request. The following sections detail these actions and their corresponding MSCML payloads. 5.8.2.1. Create the Conference Before joining any participants, the client must create the conference by sending a SIP INVITE which contains an MSCML request with a unique conference identifier. 5.8.2.2. Joining and Configuring the Coach Join the coach leg to the conference and configure its desired properties by sending a SIP INVITE containing a request. The element sets the leg's unique ID to supervisor and its mixmode to private. The corresponding MSCML request is as follows. Figure 14: Join Coach Request The media server responds as follows. Figure 15: Join Coach Response Table 5 depicts the conference configuration after the coach has been joined. Van Dyke, et al. Expires September 1, 2006 [Page 21] Internet-Draft MSCML February 2006 +-------------+------------+--------------+---------+---------+ | Participant | ID | Team Members | Mixmode | Hears | +-------------+------------+--------------+---------+---------+ | Supervisor | supervisor | none | Private | Silence | +-------------+------------+--------------+---------+---------+ Table 5: Conference After Joining the Coach Note that the client cannot configure the teammate list for the coach yet because there are no other participants in the conference. One must join a participant to the conference before one can add it as a teammate for another leg. 5.8.2.3. Joining and Configuring the Agent Join the agent leg to the conference and configure its desired properties by sending a SIP INVITE containing a request. The element sets the leg's unique ID to "agent" and sets the supervisor as a team member of the agent. Because team member relationships are symmetric, this action also adds the agent as a team member for the coach. The corresponding MSCML request is as follows. Figure 16: Join Agent Request Because the desired mixmode for this leg is full, which is the default value, there is no need to set it explicitly. The media server responds as follows. Van Dyke, et al. Expires September 1, 2006 [Page 22] Internet-Draft MSCML February 2006 Figure 17: Join Agent Response Table 6 shows the conference configuration after the agent has been joined. +-------------+------------+--------------+---------+------------+ | Participant | ID | Team Members | Mixmode | Hears | +-------------+------------+--------------+---------+------------+ | Supervisor | supervisor | agent | Private | agent | | Agent | agent | supervisor | Full | supervisor | +-------------+------------+--------------+---------+------------+ Table 6: Conference After Joining Agent 5.8.2.4. Joining and Configuring the Client Join the client leg to the conference and configure its desired properties by sending a SIP INVITE containing a request. The element simply sets the leg's unique ID to "customer." The media server does not need further configuration because the desired mixmode, full, is the default and the customer has no team members. The corresponding MSCML request is as follows. Figure 18: Join Client Request Strictly speaking, it is not a requirement that the client give the customer leg a unique ID because it will not be a team member. However, when using coached conferencing, we RECOMMEND one assign a unique ID to each leg in the initial INVITE request. Assigning a unique ID eliminates the need to set it later by sending a SIP INFO if one later desires personalized mixing for the customer leg. Van Dyke, et al. Expires September 1, 2006 [Page 23] Internet-Draft MSCML February 2006 After receiving the previous MSCML request, the media server responds as follows. Figure 19: Join Client Response Table 7 illustrates the final conference configuration. +-------------+------------+------------+---------+-----------------+ | Participant | ID | Team | Mixmode | Hears | | | | Members | | | +-------------+------------+------------+---------+-----------------+ | Supervisor | supervisor | agent | Private | customer + | | | | | | agent | | Agent | agent | supervisor | Full | customer + | | | | | | supervisor | | Customer | customer | none | Full | agent | +-------------+------------+------------+---------+-----------------+ Table 7: Final Coached Conference Configuration 5.8.2.5. Response to Configure Team With Query Action If the action attribute of has the value "query" the media server responds with the current list of team members and their number. The numteam attribute in the response indicates how many members are on the team. The following example shows that there is one team member, identified as "agent", on the team for the participant identified as "super." Figure 20: Number of Team Members If the MSCML specifies an invalid ID, the media server MUST ignore the invalid ID and treat the request as a query. Van Dyke, et al. Expires September 1, 2006 [Page 24] Internet-Draft MSCML February 2006 5.8.2.6. Exiting the Conference When the agent hangs up, the client removes the agent's leg from the supervisor's team list and from the entire conference. This process works exactly like the BYE method; the media server does not send a message to other members of the conference. The media server does not keep track of old team lists or names of old team lists. Former team members must re-join using the MSCML element as previously described. 6. Interactive Voice Response (IVR) In the IVR model, the Media Server acts as a media processing proxy for the UAC. This is particularly useful when the UAC is a media gateway or other device with limited media processing capability. The typical use case for MSCML is when there is an application server that is the MSCML client. The client can use the SIP Service URI concept (RFC 3087) to initiate a service. The client then uses RFC 4240 [2] to initiate a MSCML session on a media server. These relationships are shown in Figure 21. SIP +--------------+ Service URI | Application | /---------------| Server | /(e.g., RFC3087) +--------------+ / | MSCML / SIP | Session / +--------------+ +-----+/ RTP | | | UAC |=====================| Media Server | +-----+ | | +--------------+ Figure 21: IVR Model The IVR service supports basic Interactive Voice Response functions, playing announcements, collecting DTMF digits, and recording, based on Media Server Control Markup Language (MSCML) directives added to the message body of a SIP request. The major MSCML IVR requests are , and . Multifunction media servers MUST use the URI conventions described in RFC 4240 [2]. The service indicator for MSCML IVR MUST be set to "ivr" as shown in the following example. sip:ivr@ms.example.net Van Dyke, et al. Expires September 1, 2006 [Page 25] Internet-Draft MSCML February 2006 The VoiceXML IVR service indicator is "dialog". This service indicator MUST not be used for any other interactive voice response control mechanism. The Media Server MUST accept MSCML IVR payloads in INFO requests and MUST NOT accept MSCML IVR payloads in the initial or subsequent INVITEs. The INFO method reduces certain timing issues that occur with INVITEs and requires less processing on both the client and Media Server. The Media Server notifies the client that the command has completed through a message containing final status information and associated data such as collected DTMF digits. The Media Server does not queue IVR requests. If the Media Server receives a new IVR request while another is in progress, the media server stops the first operation and it carries out the new request. The Media Server generates a message for the first request and returns any data collected up to that point. If a client wishes to stop a request in progress but does not wish to initiate another operation, it issues a request. This also causes the Media Server to generate a message. The Media Server treats a SIP re-INVITE which modifies the established SDP parameters as an implicit request. Examples of such SDP modifications are receiving hold SDP or removing an audio or video stream. When this occurs the Media Server immediately terminates the running , or request, and sends a , indicating "reason=stopped". 6.1. Specifying Prompt Content The MSCML IVR requests support two methods of specifying content to be delivered to the user. These are the element and the prompturl attribute. Clients MUST NOT utilize both methods in a single IVR request. Clients SHOULD use the more flexible mechanism. Use of the prompturl attribute is deprecated and may not be supported in future MSCML versions. 6.1.1. Use of the Prompt Element The element MAY be included in the body of a , , or request to specify a prompt sequence to be delivered to the caller. The prompt sequence consists of one or more references to physical content files, spoken variables or dynamic URLs which return a sub-sequence of files or variables. Figure 23 shows a sample prompt block. Van Dyke, et al. Expires September 1, 2006 [Page 26] Internet-Draft MSCML February 2006 Figure 23: Prompt Block Example Table 8 describes the attributes of the element and their uses. +-------------+----------+-----+------------------------------------+ | Attribute | Default | R/O | Description | +-------------+----------+-----+------------------------------------+ | baseurl | | O | For notational convenience as well | | | | | as reducing the MSCML payload | | | | | size, the "baseurl" attribute is | | | | | used to specify a base URL which | | | | | is prepended to any other URLs in | | | | | the sequence which are not fully | | | | | qualified. | | delay | 0 | O | The "delay" attribute to the | | | | | prompt element specifies the time | | | | | to pause between repetitions of | | | | | the sequence. It has no | | | | | effect on the first iteration of | | | | | the sequence. Expressed as a time | | | | | value (Section 4.2.1) from 0 | | | | | onwards. | | duration | infinite | O | The "duration" attribute to the | | | | | prompt element controls the | | | | | maximum amount of time which may | | | | | elapse while media server repeats | | | | | the sequence. This allows the | | | | | client to set an upper bound on | | | | | the length of play. Expressed as a | | | | | time value (Section 4.2.1) from 1 | | | | | onwards or the strings "immediate" | | | | | and "infinite". "Infinite" directs | | | | | the Media Server to end play | | | | | immediately whereas "infinite" | | | | | indicates that the Media Server | | | | | imposes no limit. | Van Dyke, et al. Expires September 1, 2006 [Page 27] Internet-Draft MSCML February 2006 | gain | 0 | O | Sets the absolute gain to be | | | | | applied to the content contained | | | | | in . The value of this | | | | | attribute is specified in units of | | | | | dB. The level reverts back to its | | | | | original value when playback of | | | | | the content contained in | | | | | has completed. | | gaindelta | 0 | O | Sets the relative gain to be | | | | | applied to the content contained | | | | | in . The value of this | | | | | attribute is specified in units of | | | | | dB. The level reverts back to its | | | | | original value when playback of | | | | | the content contained in | | | | | has completed. | | rate | 0 | O | Specifies the absolute playback | | | | | rate of the content relative to | | | | | normal as either a positive | | | | | percentage (faster) or negative | | | | | percentage (slower). Any value | | | | | that attempts to set the rate | | | | | above the maximum allowed or below | | | | | the minimum allowed silently sets | | | | | the rate to the maximum or | | | | | minimum. The rate reverts back to | | | | | its original value when playback | | | | | of the content contained in | | | | | has completed. | | ratedelta | 0 | O | Specifies the playback rate of the | | | | | content relative to it's current | | | | | rate as either a positive | | | | | percentage (faster) or negative | | | | | percentage (slower). Any value | | | | | that attempts to set the rate | | | | | above the maximum allowed or below | | | | | the minimum allowed silently sets | | | | | the rate to the maximum or | | | | | minimum. The rate reverts back to | | | | | its original value when playback | | | | | of the content contained in | | | | | has completed. | Van Dyke, et al. Expires September 1, 2006 [Page 28] Internet-Draft MSCML February 2006 | locale | | O | Specifies the language and country | | | | | variant used when resolving spoken | | | | | variables. The language is defined | | | | | as a two-letter code per ISO 639. | | | | | The country variant is also | | | | | defined as a two-letter code per | | | | | ISO 3166. These codes are | | | | | concatenated with a single | | | | | underscore (%x5F) character. | | offset | 0 | O | A time value (Section 4.2.1) which | | | | | specifies the time from the | | | | | beginning of the sequence at which | | | | | play is to begin. Offset only | | | | | applies to the first repetition; | | | | | subsequent repetitions begin play | | | | | at offset 0. Allowable values are | | | | | positive time values from 0 | | | | | onwards. When the sequence | | | | | consists of multiple content files | | | | | the offset may select any point in | | | | | the sequence. If the offset value | | | | | is greater than the total time of | | | | | the sequence it will "wrap" to the | | | | | beginning and continue from there | | | | | until the media server reaches the | | | | | specified offset. | | repeat | 1 | O | The "repeat" attribute to the | | | | | prompt element controls the number | | | | | of times the media server plays | | | | | the sequence in the | | | | | element. Allowable values are | | | | | integers from 0 on and the string | | | | | "infinite" which indicates | | | | | repetition should occur | | | | | indefinitely. For example, | | | | | "repeat=2" means the sequence will | | | | | be played twice and "repeat=0", | | | | | which is allowed, means the | | | | | sequence is not played. | Van Dyke, et al. Expires September 1, 2006 [Page 29] Internet-Draft MSCML February 2006 | stoponerror | no | O | Controls media server handling and | | | | | reporting of errors encountered | | | | | when retrieving remote content. If | | | | | set to "yes" content play will end | | | | | if a fetch error occurs and the | | | | | response will contain details | | | | | regarding the failure. If set to | | | | | "no" the media server will | | | | | silently move on to the next URL | | | | | in the sequence if a fetch failure | | | | | occurs. | +-------------+----------+-----+------------------------------------+ Table 8: Prompt Attributes Clients MUST NOT include both 'gain' and 'gaindelta' attributes within a single element. Media server's SHOULD support rate controls for content. However, media servers MAY silently ignore rate change requests if content limitations do not allow the request to be honored. Clients MUST NOT include both 'rate' and 'ratedelta' attributes within a single element. 6.1.1.1. Figure 52: Managecontent Example Note that the client can change the temporary file name assigned by the media server as part of this operation as shown. The media server returns a response similar to the following. Figure 53: Managecontent Response If the request is ambiguous, the media server MUST return a status code of "400" and text "Bad Request." If the media server is unable to execute a syntactically correct and unambiguous request it MUST return a "500" status code with the text "Server Error." For example, if the local file system access restrictions described earlier prevent deletion of the specified file the media server returns the following. Van Dyke, et al. Expires September 1, 2006 [Page 64] Internet-Draft MSCML February 2006 Figure 54: Managcontent Error Response The "reason" attribute in the response conveys additional details on the server error that occurred. If there is a network or remote server error, the media server provides detailed error information in the element contained in the media server response. The following example shows that the media server received a 503 error from the remote web server. Figure 55: Managcontent Storage Error Response 9. Fax Processing 9.1. Recording a Fax The request directs the Media Server to process a fax in answer mode. The reason for a request separate from is that the media server needs to know to process the T.30 [18] or T.38 [19] fax protocols. The request has multiple attributes and one child element, . These attributes are described in Table 26. Van Dyke, et al. Expires September 1, 2006 [Page 65] Internet-Draft MSCML February 2006 +----------------+---------+-----+----------------------------------+ | Attribute | Default | R/O | Description | +----------------+---------+-----+----------------------------------+ | lclid | "" | O | A string that identifies the | | | | | called station. | | prompturl | | O | The URL of the content to be | | | | | retrieved and played. The target | | | | | may be a local or remote (NFS) | | | | | "file://" scheme URL or an | | | | | "http://" or "https://" scheme | | | | | URL. NOTE: Use of this attribute | | | | | is deprecated. | | promptencoding | | O | Specifies the content encoding | | | | | for files that do not have a | | | | | 'tif' or 'tiff' extension. The | | | | | only allowable value is "tiff". | | | | | This attribute only affects | | | | | "file://" scheme URLs. NOTE: Use | | | | | of this attribute is deprecated. | | recurl | | O | Specifies the target URL for the | | | | | recorded content. | | rmtid | | O | Specifies the calling station | | | | | identifier of the remote | | | | | terminal. If present, the media | | | | | server MUST reject transactions | | | | | with the remote terminal if the | | | | | remote terminal's identifier | | | | | does not match the value of | | | | | 'rmtid'. | +----------------+---------+-----+----------------------------------+ Table 26: Faxrecord Attributes Clients SHOULD use the more flexible mechanism for specifying fax content. Use of the 'prompturl' attribute is deprecated and may not be supported in future MSCML versions. The element is described in Section 6.1.1. A element sent in a request MUST not contain elements. Media servers MUST support local and remote (NFS) "file://" scheme URL's in the "recurl" attribute. MSCML supports "http://" and "https://" scheme URLs indirectly through the (Section 8) request. The request operates in one of three modes: receive, poll, and turnaround poll. The combination of or 'prompturl' attribute and 'recurl' attribute define the mode. Table 27 describes these modes in detail. The 'prompt' column in the Van Dyke, et al. Expires September 1, 2006 [Page 66] Internet-Draft MSCML February 2006 table has the value 'yes' if the request has either a element or 'prompturl' attribute. +--------+--------+---------+---------------------------------------+ | prompt | recurl | Mode | Operation | +--------+--------+---------+---------------------------------------+ | no | no | Invalid | Request fails. | | no | yes | Receive | Record the fax to the target URL | | | | | specified in 'recurl'. | | yes | no | Poll | Send fax from source specified in the | | | | | element or 'prompturl' | | | | | attribute. If there is a 'rmtid', it | | | | | MUST match the remote terminal's | | | | | identifier, or the request will fail. | | yes | yes | TP | Turnaround Poll (TP) mode. If the | | | | | remote terminal wishes to transmit, | | | | | the media server records the fax to | | | | | the target URL specified in 'recurl'. | | | | | If the remote terminal wishes to | | | | | receive, the media server sends the | | | | | fax from the source URL contained in | | | | | or 'prompturl'. If there is | | | | | a 'rmtid', it MUST match remote | | | | | terminal's identifier, or the send | | | | | request will fail. A receive | | | | | operation will still succeed, | | | | | however. | +--------+--------+---------+---------------------------------------+ Table 27: Fax Receive Modes In receive mode, the media server receives the fax and writes the fax data to the target URL specified by the 'recurl' attribute. In poll mode, the media server sends a fax, but as a polled (called) device. In turnaround poll mode, the media server will record a fax that the remote machine sends. If the remote machine requests a transmission, then the media server will send the fax. When transmitting a fax the media server will advertise that it can receive faxes in the DIS message. Likewise, when receiving a fax the media server will advertise that it can send faxes in the DIS message. The media server MUST flush any quarantined digits when it receives a request. Van Dyke, et al. Expires September 1, 2006 [Page 67] Internet-Draft MSCML February 2006 9.2. Sending a Fax The request directs the Media Server to process a fax in originate mode. The reason for a request separate from is that the Media Server needs to know to process the T.30 [18] or T.38 [19] fax protocols. The request has multiple attributes and one child element, . These attributes are described in Table 28. +----------------+---------+-----+----------------------------------+ | Attribute | Default | R/O | Description | +----------------+---------+-----+----------------------------------+ | lclid | | O | A string that identifies the | | | | | called station. | | prompturl | | O | The URL of the content to be | | | | | retrieved and played. The target | | | | | may be a local or remote (NFS) | | | | | "file://" scheme URL or an | | | | | "http://" or "https://" scheme | | | | | URL. NOTE: Use of this attribute | | | | | is deprecated. | | promptencoding | | O | Specifies the content encoding | | | | | for files that do not have a | | | | | 'tif' or 'tiff' extension. The | | | | | only allowable value is "tiff". | | | | | This attribute only affects | | | | | "file://" scheme URLs. NOTE: Use | | | | | of this attribute is deprecated. | | recurl | | O | Specifies the target URL for the | | | | | recorded content. | | rmtid | | O | Specifies the calling station | | | | | identifier of the remote | | | | | terminal. If present, the media | | | | | server MUST reject transactions | | | | | with the remote terminal if the | | | | | remote terminal's identifier | | | | | does not match the value of | | | | | 'rmtid'. | +----------------+---------+-----+----------------------------------+ Table 28: Faxplay Attributes Clients SHOULD use the more flexible mechanism for specifying fax content. Use of the 'prompturl' attribute is deprecated and may not be supported in future MSCML versions. The element is described in Section 6.1.1. A element sent in a request MUST not contain elements. Van Dyke, et al. Expires September 1, 2006 [Page 68] Internet-Draft MSCML February 2006 Media servers MUST support local and remote (NFS) "file://" scheme URL's in the "recurl" attribute. MSCML supports "http://" and "https://" scheme URLs indirectly through the (Section 8) request. The request operates in one of three modes: send, remote poll, and turnaround poll. The combination of or 'prompturl' attribute and 'recurl' attribute define the mode. Table 29 describes these modes in detail. The 'prompt' column in the table has the value 'yes' if the request has either a element or 'prompturl' attribute. +--------+--------+---------+---------------------------------------+ | prompt | recurl | Mode | Operation | +--------+--------+---------+---------------------------------------+ | no | no | Invalid | Request fails. | | yes | no | Send | Send fax from source specified in the | | | | | element or 'prompturl' | | | | | attribute. If there is a 'rmtid', it | | | | | MUST match the remote terminal's | | | | | identifier, or the request will fail. | | | | | If there is a 'rmtid', it must match | | | | | remote terminal's identifier, or the | | | | | receive request will fail. | | no | yes | Poll | Send fax from source specified in the | | | | | element or 'prompturl' | | | | | attribute, assuming the remote | | | | | terminal specifies it can receive a | | | | | fax in its DIS message. It the remote | | | | | terminal does not support reverse | | | | | polling, the request will fail. If | | | | | 'rmtid' is specified, it must match | | | | | remote terminal's identifier, or the | | | | | request will fail. | | yes | yes | TP | Turnaround Poll (TP) mode. If the | | | | | remote terminal wishes to transmit, | | | | | the media server records the fax to | | | | | the target URL specified in 'recurl'. | | | | | If the remote terminal wishes to | | | | | receive, the media server sends the | | | | | fax from the source URL contained in | | | | | or 'prompturl'. If there is | | | | | a 'rmtid', it MUST match remote | | | | | terminal's identifier, or the send | | | | | request will fail. A receive | | | | | operation will still succeed, | | | | | however. | +--------+--------+---------+---------------------------------------+ Van Dyke, et al. Expires September 1, 2006 [Page 69] Internet-Draft MSCML February 2006 Table 29: Fax Send Modes In send mode, the media server sends the fax. In remote poll mode, the client places a call on behalf of the media server. The media server requests a fax transmission from the remote fax terminal. In turnaround poll mode, the media server will record a fax that the remote machine sends. If the remote machine requests a transmission, then the media server will send the fax. When transmitting a fax the media server will advertise that it can receive faxes in the DIS message. Likewise, when receiving a fax the media server will advertise that it can send faxes in the DIS message. The Media Server MUST flush any quarantined digits when it receives a request. 10. MSCML Response Attributes and Elements 10.1. Mechanism The Media Server acknowledges receipt of a client MSCML request sent in a SIP INVITE by sending a response of either 200 OK or 415 Bad Media Type. The Media Server responds with 415 when the SIP request contains a content type other than "application/sdp" or "application/ mediaservercontrol+xml". The Media Server acknowledges receipt of a client MSCML request sent in a SIP INFO with a 200 OK or 415 Bad Media Type. The Media Server responds with 415 if the INFO request contains a content type other than "application/mediaservercontrol+xml". The Media Server transports the MSCML message in a SIP INFO request. If there is an error in the request or the Media Server cannot complete the request, the Media Server sends the message very shortly after receiving the request. If the request is able to proceed, the contains final status information as described below. 10.2. Base Attributes All MSCML responses have the basic attributes defined in Table 30. Van Dyke, et al. Expires September 1, 2006 [Page 70] Internet-Draft MSCML February 2006 +-----------+---------+-----+---------------------------------------+ | Attribute | Default | R/O | Description | +-----------+---------+-----+---------------------------------------+ | id | | O | Echoes the client defined ID for | | | | | contained in the request. | | request | | R | Specifies the MSCML request type that | | | | | generated the response. Allowable | | | | | values are "configure_conference", | | | | | "configure_leg", "play", | | | | | "playcollect", "playrecord", "stop", | | | | | "faxplay", "faxrecord" and | | | | | "managecontent". | | code | | R | The final status code for the | | | | | request. MSCML uses a subset of the | | | | | status classes defined in RFC 3261 | | | | | [4]. In MSCML, 2XX responses indicate | | | | | success, 4XX responses indicate | | | | | client error and 5XX responses | | | | | indicate an error on the Media | | | | | Server. There are no 1XX, 3XX or 6XX | | | | | status codes in MSCML. | | text | | R | The human readable reason phrase | | | | | associated with the status code. | +-----------+---------+-----+---------------------------------------+ Table 30: Basic MSCML Response Attributes Responses to and requests contain only the attributes above. MSCML responses to other requests MAY contain additional request specific attributes and elements. These are described below. 10.3. Response Attributes and Elements for Responses to requests have only the base response attributes defined in Table 30. However, when the request contains a element the response includes a element describing the teammate configuration for that leg. The attributes of the element are shown in Table 31. +-----------+---------+-----+---------------------------------------+ | Attribute | Default | R/O | Description | +-----------+---------+-----+---------------------------------------+ | id | | R | The client defined unique identifier | | | | | for the conference leg. | | numteam | | R | The number of team members for the | | | | | leg. | +-----------+---------+-----+---------------------------------------+ Van Dyke, et al. Expires September 1, 2006 [Page 71] Internet-Draft MSCML February 2006 Table 31: Attributes for Additional information on each team member is conveyed by child elements contained within . Each teammate is represented by a single element in the list. The element has a single attribute as described in Table 32. +-----------+---------+-----+---------------------------------------+ | Attribute | Default | R/O | Description | +-----------+---------+-----+---------------------------------------+ | id | | R | The client defined unique identifier | | | | | for the teammate leg. | +-----------+---------+-----+---------------------------------------+ Table 32: Attributes for 10.4. Response Attributes and Elements for In addition to the base response attributes defined in Table 30, responses to requests have the additional attributes described in Table 33. +--------------+---------+-----+------------------------------------+ | Attribute | Default | R/O | Description | +--------------+---------+-----+------------------------------------+ | reason | | O | For requests that do not complete | | | | | immediately, the "reason" | | | | | attribute conveys additional | | | | | information regarding why the | | | | | command completed. Possible values | | | | | are "stopped", indicating an | | | | | explicit or implicit | | | | | request was received and "EOF" | | | | | indicating that the end of the | | | | | specified sequence of URLs was | | | | | reached. | | playduration | | R | A time value (Section 4.2.1) that | | | | | returns the duration of the | | | | | associated content playout. | Van Dyke, et al. Expires September 1, 2006 [Page 72] Internet-Draft MSCML February 2006 | playoffset | | R | A time value (Section 4.2.1) that | | | | | returns the time offset into the | | | | | specified content sequence where | | | | | play was terminated. If the | | | | | initial "offset" value in the | | | | | sequence was "0", then | | | | | "playduration" and "playoffset" | | | | | are equal. However, if the the | | | | | initial offset had some other | | | | | value "playoffset" serves as a | | | | | bookmark for the client to resume | | | | | play in a subsequent request. | +--------------+---------+-----+------------------------------------+ Table 33: MSCML Response Attributes for 10.4.1. Reporting Content Retrieval Errors If the associated request set "stoponerror=yes" in and an error occurred while retrieving the specified content the response will include an element detailing the problem. This element contains the response information received from the remote content server. The element has the attributes described in Table 34. +-----------+---------+-----+---------------------------------------+ | Attribute | Default | R/O | Description | +-----------+---------+-----+---------------------------------------+ | code | | R | The status code returned by the | | | | | remote content server. For example, a | | | | | web server might return 404 to | | | | | indicate that the requested content | | | | | was not found. | | text | | R | The human readable reason phrase | | | | | returned by the remote content | | | | | server. For example, the reason | | | | | phrase "Not Found" would be returned | | | | | if the requested content was not | | | | | found | | context | | R | Contains the content URL that was | | | | | being fetched when the retrieval | | | | | error occurred. This enables the | | | | | client to know precisely which URL in | | | | | a sequence caused the problem. | +-----------+---------+-----+---------------------------------------+ Table 34: Attributes of Van Dyke, et al. Expires September 1, 2006 [Page 73] Internet-Draft MSCML February 2006 An element MAY be present in the response to any request which contains a child element. 10.5. Response Attributes and Elements for In addition to the base response attributes defined in Table 30, responses to requests have the additional attributes described in Table 35. +--------------+---------+-----+------------------------------------+ | Attribute | Default | R/O | Description | +--------------+---------+-----+------------------------------------+ | reason | | O | For requests that do not complete | | | | | immediately, the "reason" | | | | | attribute conveys additional | | | | | information regarding why the | | | | | command completed. Possible values | | | | | are "stopped", indicating an | | | | | explicit or implicit | | | | | request was received, "match" | | | | | meaning a DTMF grammar was | | | | | matched, "timeout" indicating that | | | | | no DTMF input was received before | | | | | one of the collection timers | | | | | expired, and "returnkey" or | | | | | "escapekey" meaning the DTMF digit | | | | | mapped to that key was detected. | | | | | the return key or escape key | | | | | terminated the operation, | | | | | respectively. | | playduration | | R | A time value (Section 4.2.1) that | | | | | returns the duration of the | | | | | associated content playout. If the | | | | | caller barged the prompt this | | | | | value will reflect the play | | | | | duration up to that event. | Van Dyke, et al. Expires September 1, 2006 [Page 74] Internet-Draft MSCML February 2006 | playoffset | | R | A time value (Section 4.2.1) that | | | | | returns the time offset into the | | | | | specified content sequence where | | | | | play was terminated. If the | | | | | initial "offset" value in the | | | | | sequence was "0", then | | | | | "playduration" and "playoffset" | | | | | are equal. However, if the the | | | | | initial offset had some other | | | | | value "playoffset" serves as a | | | | | bookmark for the client to resume | | | | | play in a subsequent request. If | | | | | the caller barged the prompt this | | | | | value will reflect the time offset | | | | | at which barge-in occurred. | | digits | | R | Contains the collected DTMF input | | | | | characters. If no DTMF input was | | | | | collected this attribute is set to | | | | | the empty string (""). | | name | | O* | The client defined name of the | | | | | DTMF grammar that was matched. | | | | | *This attribute is required if the | | | | | "name" attribute was set in the | | | | | matching DTMF grammar. | +--------------+---------+-----+------------------------------------+ Table 35: MSCML Response Attributes for Responses to requests MAY include an element as described in Section 10.4.1. 10.6. Response Attributes and Elements for In addition to the base response attributes defined in Table 30, responses to requests have the additional attributes described in Table 36. Van Dyke, et al. Expires September 1, 2006 [Page 75] Internet-Draft MSCML February 2006 +--------------+---------+-----+------------------------------------+ | Attribute | Default | R/O | Description | +--------------+---------+-----+------------------------------------+ | reason | | O | For requests that do not complete | | | | | immediately, the "reason" | | | | | attribute conveys additional | | | | | information regarding why the | | | | | command completed. Possible values | | | | | are "stopped", indicating an | | | | | explicit or implicit | | | | | request was received, "digit" | | | | | meaning a DTMF digit was detected | | | | | so the prompt phase was barged, | | | | | "init_silence" meaning the | | | | | recording terminated because | | | | | because of no input, "end_silence" | | | | | meaning the recording was | | | | | terminated because the | | | | | "endsilence" timer elapsed, | | | | | "max_duration" indicating that the | | | | | maximum time for the recording was | | | | | reached, "escapekey" indicating | | | | | the DTMF input mapped to | | | | | "escapekey" was detected, thus | | | | | terminating the recording and | | | | | "error" indicating a general | | | | | operation failure. | | playduration | | R | A time value (Section 4.2.1) that | | | | | returns the duration of the | | | | | associated content playout. If the | | | | | caller barged the prompt this | | | | | value will reflect the play | | | | | duration up to that event. | | playoffset | | R | A time value (Section 4.2.1) that | | | | | returns the time offset into the | | | | | specified content sequence where | | | | | play was terminated. If the | | | | | initial "offset" value in the | | | | | sequence was "0", then | | | | | "playduration" and "playoffset" | | | | | are equal. However, if the the | | | | | initial offset had some other | | | | | value "playoffset" serves as a | | | | | bookmark for the client to resume | | | | | play in a subsequent request. If | | | | | the caller barged the prompt this | | | | | value will reflect the time offset | | | | | at which barge-in occurred. | Van Dyke, et al. Expires September 1, 2006 [Page 76] Internet-Draft MSCML February 2006 | digits | | R | Contains the DTMF digit that | | | | | terminated the recording. If no | | | | | DTMF input was detected this | | | | | attribute is set to the empty | | | | | string (""). | | reclength | | R | The length of the recorded content | | | | | in bytes. | | recduration | | R | A time value (Section 4.2.1) | | | | | indicating the elapsed duration of | | | | | the recording. | +--------------+---------+-----+------------------------------------+ Table 36: MSCML Response Attributes for Responses to requests MAY include an element as described in Section 10.4.1. 10.7. Response Attributes and Elements for Responses to requests have only the base response attributes defined in Table 30. If a content transfer error occurs while executing the request the response will also contain an element as described in Section 10.4.1. 10.8. Response Attributes and Elements for and In addition to the base response attributes defined in Table 30, responses to and requests have the additional attributes described in Table 37. Van Dyke, et al. Expires September 1, 2006 [Page 77] Internet-Draft MSCML February 2006 +----------------+---------+-----+----------------------------------+ | Attribute | Default | R/O | Description | +----------------+---------+-----+----------------------------------+ | reason | | R | For requests that do not | | | | | complete immediately, the | | | | | "reason" attribute conveys | | | | | additional information regarding | | | | | why the command completed. | | | | | Possible values are "stopped", | | | | | indicating an explicit or | | | | | implicit request was | | | | | received, "complete" indicating | | | | | successful completion, even if | | | | | there were bad lines or minor | | | | | negotiation problems (e.g. a DCN | | | | | was received), "disconnect" | | | | | meaning that the session was | | | | | disconnected and "notfax" | | | | | indicationg that no DIS or DCS | | | | | was received on the connection. | | pages_received | | O* | Indicates the number of fax | | | | | pages received. *Required if any | | | | | pages were received. | | pages_sent | | O* | Indicates the number of fax | | | | | pages sent. *Required if any | | | | | pages were sent. | | faxcode | | R | The value of the "faxcode" | | | | | attribute is the binary-or of | | | | | the bit patterns defined in | | | | | Table 38. | +----------------+---------+-----+----------------------------------+ Table 37: MSCML Response Attributes for and Van Dyke, et al. Expires September 1, 2006 [Page 78] Internet-Draft MSCML February 2006 +------+--------------------------------------+ | Mask | description | +------+--------------------------------------+ | 0 | Operation Failed | | 1 | Operation Succeeded | | 2 | Partial Success | | 4 | Image received and placed in recurl | | 8 | Image sent from specified source URL | | 16 | rmtid did not match | | 32 | Error reading source URL | | 64 | Error writing recurl | | 128 | Negotiation failure on send phase | | 256 | Negotiation failure on receive phase | | 512 | Reserved | | 1024 | Irrecoverable IP packet loss | | 2048 | Line errors in received image | +------+--------------------------------------+ Table 38: Faxcode Mask Responses to and requests MAY include an element as described in Section 10.4.1. 11. Formal Syntax The following syntax specification uses XML Schema as described in XML [7]. 11.1. Schema Van Dyke, et al. Expires September 1, 2006 [Page 80] Internet-Draft MSCML February 2006 Van Dyke, et al. Expires September 1, 2006 [Page 81] Internet-Draft MSCML February 2006 Van Dyke, et al. Expires September 1, 2006 [Page 82] Internet-Draft MSCML February 2006 Van Dyke, et al. Expires September 1, 2006 [Page 83] Internet-Draft MSCML February 2006 Van Dyke, et al. Expires September 1, 2006 [Page 84] Internet-Draft MSCML February 2006 Van Dyke, et al. Expires September 1, 2006 [Page 85] Internet-Draft MSCML February 2006 Van Dyke, et al. Expires September 1, 2006 [Page 86] Internet-Draft MSCML February 2006 Van Dyke, et al. Expires September 1, 2006 [Page 87] Internet-Draft MSCML February 2006 Van Dyke, et al. Expires September 1, 2006 [Page 88] Internet-Draft MSCML February 2006 Van Dyke, et al. Expires September 1, 2006 [Page 89] Internet-Draft MSCML February 2006 12. IANA Considerations 12.1. IANA Registration of MIME media type application/ mediaservercontrol+xml MIME media type name: application MIME subtype name: mediaservercontrol+xml Required parameters: none Optional parameters: charset charset This parameter has identical semantics to the charset parameter of the "application/xml" media type as specified in XML Media Types [8]. Van Dyke, et al. Expires September 1, 2006 [Page 90] Internet-Draft MSCML February 2006 Encoding considerations: See RFC3023 [8]. Interoperability considerations: See RFC2023 [8] and RFCXXXX. Published specification: RFCXXXX Applications which use this media type: Multimedia, enhanced conferencing and interactive applications. Personal and email address for further information: eburger@brooktrout.com [29] Intended usage: COMMON 13. Security Considerations Because media flows through a media server in a conference, the media server itself MUST protect the integrity, confidentiality, and security of the sessions. It should not be possible for a conference participant, on her own behalf, to be able to "tap in" to another conference without proper authorization. Because conferencing is a high value application, the media server SHOULD implement appropriate security measures. This includes, but not limited to, access lists for application servers. That is, the media server only allows a select list of application or proxy servers to create conferences, invite participants to sessions, etc. Note that the mechanisms for such security, like private networks, shared certificates, MAC white/black lists, are beyond the scope of this document. Security concerns are one important reason MSCML limits requests with conference scope to a separate control leg per conference. MSCML uses the simple, proven, Internet-scale security model of SIP to determine if a client is who they say they are (authentication) and if they are allowed to create and manipulate a conference. However, the security model to enable a control leg to manipulate arbitrary conferences on the media server is extremely difficult. One would need to not only authenticate and authorize the basic conference primitives, but privacy considerations require policies for one client to access another client's conferences, even if the two clients are on the same host. For example, if the media server allowed any control leg to control any conference, an authorized, but unrelated client could maliciously attach itself to an existing session and record or tap the conversation without the participant's knowledge or consent. Participants give implicit authorization to their applications by virtue of the INVITE to the application. However, there is no trust, explicit or implicit, between the users of one service and a distinct client of another service. Van Dyke, et al. Expires September 1, 2006 [Page 91] Internet-Draft MSCML February 2006 Because of the sensitive nature of collected data, such as credit card numbers or other identifying information, the media server MUST support sips: and TLS. Clients, who presumably know the value of the information they collect, as well as the privacy expectations of their users, are free to use clear text signaling or encrypted, secure signaling, depending on the application's needs. Likewise, the media server SHOULD support SRTP [9]. Again, the clients are free to negotiate the appropriate level of media security. All MSCML messages are sent within an INVITE created SIP dialog. As a result it would be difficult for an entity other than the original requestor to interfere with an established MSCML session, as this would require detailed information on the dialog state. This allows multiple applications to simultaneously utilize the resources of a single media server without interfering with one another. As an XML markup, all of the security considerations of RFC3023 [8] apply. 14. References 14.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Burger, E., Van Dyke, J., and A. Spitzer, "Basic Network Media Services with SIP", RFC 4240, December 2005. [3] Donovan, S., "The SIP INFO Method", RFC 2976, October 2000. [4] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [5] "Network call signalling protocol for the delivery of time- critical services over cable television networks using cable modems", ITU-T J.162, March 2001. [6] Groves, C., Pantaleo, M., Anderson, T., and T. Taylor, "Gateway Control Protocol Version 1", RFC 3525, June 2003. [7] Thompson, H., Beech, D., Maloney, M., and N. Mendelsohn, "XML Schema Part 1: Structures", W3C REC REC-xmlschema-1-20010502, May 2001. [8] Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types", Van Dyke, et al. Expires September 1, 2006 [Page 92] Internet-Draft MSCML February 2006 RFC 3023, January 2001. [9] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, "The Secure Real-time Transport Protocol (SRTP)", RFC 3711, March 2004. 14.2. Informative References [10] Levin, O., "Session Initiation Protocol Call Control - Conferencing for User Agents", draft-ietf-sipping-cc-conferencing-07 (work in progress), June 2005. [11] Carter, J., Danielsen, P., Hunt, A., Ferrans, J., Lucas, B., Porter, B., Rehor, K., Tryphonas, S., McGlashan, S., and D. Burnett, "Voice Extensible Markup Language (VoiceXML) Version 2.0", W3C REC REC-voicexml20-20040316, March 2004. [12] International Packet Communications Consortium, "IPCC Reference Architecture V2", June 2002. [13] European Telecommunications Standards Institute, "Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); IP Multimedia Subsystem (IMS); Stage 2 (3GPP TS 23.228 version 7.2.0 Release 7)", December 2005. [14] Hollenbeck, S., Rose, M., and L. Masinter, "Guidelines for the Use of Extensible Markup Language (XML) within IETF Protocols", BCP 70, RFC 3470, January 2003. [15] Jacobs, I., Lie, H., Bos, B., and C. Lilley, "Cascading Style Sheets, level 2 (CSS2) Specification", W3C REC REC-CSS2- 19980512, May 1998. [16] Rosenberg, J., "A Session Initiation Protocol (SIP) Event Package for Conference State", draft-ietf-sipping-conference-package-12 (work in progress), July 2005. [17] Cable Television Laboratories, Inc., "Audio Server Protocol", January 2005. [18] "Procedures for document facsimile transmission in the general switched telephone network", Recommendation T.30, April 1999. [19] "Procedures for real-time Group 3 facsimile communication over IP networks", Recommendation T.38, March 2002. Van Dyke, et al. Expires September 1, 2006 [Page 93] Internet-Draft MSCML February 2006 [20] Institute of Electrical and Electronics Engineers, "Information Technology - Portable Operating System Interface (POSIX) - Part 1: Base Definitions, Chapter 9", IEEE Standard 1003.1, June 2001. [21] Burger, E. and M. Dolly, "Keypad Stimulus Protocol (KPML)", draft-IETF-sipping-kpml-07 (work in progress), December 2004. [22] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821, April 2001. [23] Campbell, B., "The Message Session Relay Protocol", draft-ietf-simple-message-sessions-09 (work in progress), October 2004. URIs [24] [25] [26] [27] [28] [29] Appendix A. Regex Grammar Syntax The regular expression syntax used in MSCML is a telephony-oriented subset of POSIX Extended Regular Expressions (ERE) [20] termed Digit REGular EXpression (DRegex). This syntax was first described in KPML [21]. DRegex includes ordinary characters, special characters, bracket expressions and interval expressions. These entities are defined in the list below. character matches digits 0-9, *, #, and A-D (case insensitive) * matches the * character # matches the # character Van Dyke, et al. Expires September 1, 2006 [Page 94] Internet-Draft MSCML February 2006 [character selector] matches any character in selector [range1-range2] matches any character in range from range1 to range2, inclusive x matches any digit 0-9 {m} matches m repetitions of the previous pattern {m,} matches m or more repetitions of the previous pattern {,n} matches at most n (including zero) repetitions of the previous pattern {m,n} at least m and at most n repetitions of the previous pattern L the presence of 'L' in any regex expression causes the Media Server to enable "long" digit detection mode. See Section 7.1 for the definition of "long" digits. Table 39 illustrates DRegex usage through examples. +--------------+--------------------------------------------+ | Example | Description | +--------------+--------------------------------------------+ | 1 | Matches the digit 1 | | [179] | Matches 1, 7, or 9 | | [2-9] | Matches 2, 3, 4, 5, 6, 7, 8, 9 | | [02-46-9A-D] | Matches 0, 2, 3, 4, 6, 7, 8, 9, A, B, C, D | | x | Matches 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 | | *6[179#] | Matches *61, *67, *69, or *6# | | x{10} | Ten digits (0-9) | | 011x{7,15} | 011 followed by seven to fifteen digits | | L* | Long star | +--------------+--------------------------------------------+ Table 39: DRegex Examples Appendix B. Contributors Jeff Van Dyke and Andy Spitzer did the concept, development, documentation, and execution for MSCML at SnowShore Networks, Inc. Andy Spitzer's orignal work at The Telephone Connection, Inc. influenced the IVR implementation. Mary Ann Leekley implemented the personalized mix feature and several other enhancements. Cliff Schornak of Commetrex and Jeff Van Dyke developed the facsimile service. Jai Cauvet, Rolando Herrero, Srinivas Motamarri and Ashish Patel contributed greatly by testing MSCML. Van Dyke, et al. Expires September 1, 2006 [Page 95] Internet-Draft MSCML February 2006 Appendix C. Acknowledgements The following individuals significantly assisted in the development, direction, or, most importantly, debugging of MSCML: o Brian Badger and Phil Crable from Verizon Business o Stephane Bastien from BroadSoft o Peter Danielsen of Lucent Technologies o Kevin Flemming formerly of SnowShore Networks, Inc. o Wesley Hicks and Ravindra Kabre, formerly from Sonus Networks o Jon Hinckley from SkyWave/Sestro o Terence Lobo formerly of SnowShore Networks, Inc. o Kunal Nawale formerly of SnowShore Networks, Inc. o Edwina Nowicki formerly of SnowShore Networks, Inc. o Diana Rawlins and Sharadha Vijay formerly of WorldCom o Gaurav Srivastva and Subhash Verma from BayPackets o Kevin Summers from Sonus Networks o Tim Wong from at&t The authors would also like to thank Scotty Farber for applying her considerable tecnhnical writing expertise to the documentation of MSCML. Van Dyke, et al. Expires September 1, 2006 [Page 96] Internet-Draft MSCML February 2006 Authors' Addresses Jeff Van Dyke Brooktrout Technology, Inc. 18 Keewaydin Dr. Salem, NH 03079 USA Email: jvandyke@brooktrout.com Eric Burger (editor) Brooktrout Technology, Inc. 18 Keewaydin Dr. Salem, NH 03079 USA Email: eburger@brooktrout.com Andy Spitzer Brooktrout Technology, Inc. 18 Keewaydin Dr. Salem, NH 03079 USA Email: woof@brooktrout.com Van Dyke, et al. Expires September 1, 2006 [Page 97] Internet-Draft MSCML February 2006 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Van Dyke, et al. Expires September 1, 2006 [Page 98]