Internet Engineering Task Force Kushanava Laha Internet Draft Vikram Nair Document: draft-ietf-megaco-r2package-03.txt Hughes Software Systems Category: Standards Track March 2003 Megaco/H.248 R2 Package Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [1]. 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 obsolete 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. 1. Abstract This document is work in progress and defines the R2 package for the Megaco/H.248 Protocol that can be used to exchange call setup supervisory and control information between a Media Gateway (MG) and a Media Gateway Controller (MGC) to realize Signaling System R2 at a VoIP Gateway. It is intended to satisfy the requirements in section 12 of the Megaco/H.248 protocol [2]. 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [3]. 3. Document Organization The subsequent portion of this draft is organized into the following major sections: * Introduction * Assumptions Laha, Nair Standards Track - Expires September 2003 1 Megaco/H.248 R2 Package * R2 package * Procedures * References * Author's Address 4. Introduction Signaling System R2 is used for international/national signaling for both automatic and semiautomatic working. It allows for rapid call set-up by providing sufficient signals in both directions to permit the transmission of numerical and other information relating to the called and calling subscriber lines and to increase routing facilities. Terminations (signaling trunks) at the MG, implementing signaling system R2 SHOULD realize the R2 package. The R2 package presented in this draft extends the basic CAS package (bcas) [4]. The bcas package defines the basic properties that need to be supported by a termination in MG to realize any CAS protocol. It also specifies events and signals required to be exchanged between the MGC and MG to execute basic line signaling procedures for any CAS protocol (R2 Signaling System inclusive). The R2 package adds the R2 address signaling parameters in the form of additional properties, events and signals to complete the realization of Signaling System R2 at a VoIP Gateway. The forward and backward compelled register signaling sequence for exchanging call setup control information SHALL be executed in the MG. Signaling System R2 defines several numbered (digit) and enumerated (non-digit) components of the call set-up control information. The numbered call setup-up control information components considered in the R2 package are the destination number, source number and country code. The enumerated call set-up control information components considered are echo suppression information, calling subscriber category, discriminating indicator, nature of circuit, subscriber line status and congestion information. Of these, the numbered components and the following enumerated components - echo suppression information, calling subscriber category, discriminating indicator and nature of circuit, are collectively termed as address parameters as they collectively convey the complete address information required for call set-up in Signaling system R2. They are also the components required at the minimum by the outgoing MG in order to start the compelling action. The R2 package defines a "r2addr" signal and event used for exchanging address signaling parameters between MG and MGC. To gracefully handle time sensitive issues governing the compelling sequence and to keep the MGC transparent of implementation specific compelling at MG, the following simple guidelines have been observed while defining the R2 package. Laha, Nair Standards Track - Expires September 2003 2 Megaco/H.248 R2 Package o All numbered address parameters are exchanged as complete digit strings between the MG and MGC containing all the digits. Digit by digit reporting or signaling of numbered address parameters are not allowed between the MG and MGC. o It is necessary that the outgoing MG is equipped with all the address parameters before it can start with the outpulsing compelling sequence. The MGC, therefore, sends the address parameters to the outgoing MG as additional parameters in one composite R2 Address signal. o The MG behaving as an incoming R2 end, SHALL compel and collect all the address parameters as per the provisioned compelling sequence. Flexibility is there in the package for the MGC to solicit each address parameter as separate events or as a single composite event - the "r2addr" event, where the collected address parameters are ObservedEvents Descriptor parameters to the event. Signals and events related to only basic R2 signaling operation for automatic or semi-automatic working, have been considered in the R2 package. Variants of R2 signaling MAY define new supervisory (line) and call set-up control (register) signals to introduce features such as re-answering, trunk offering, re-ring, operator break-in etc, to name a few. As there is no single standard mechanism to implement such features (they vary from country to country), they have not been considered in this package. However it is possible to realize such features on the MEGACO interface, by defining additional signals and events in other packages that either extend this basic R2 package or are to be used in conjunction with this R2 package. 5. Assumptions a) As shown in the diagram below, MG can be connected to R2 exchange for R2 compelled signaling, peer MG for media transport and MGC for exchanging R2 signaling information using MEGACO/H.248 with R2 package. +-----+ +-MEGACO-| MGC |-MEGACO-+ | +-----+ | | | (~~~~~~) +--+--+ +--+--+ (~~~~~~) ( PSTN )====R2=====| MG1 |------RTP--------| MG2 |====R2=====( PSTN ) (~~~~~~) +-----+ +-----+ (~~~~~~) [Call origination] [Incoming MG] [Outgoing MG] [Call Termination] Incoming - Outgoing convention ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This draft uses the following convention for incoming / outgoing MG o Incoming MG: R2 exchange initiates the call signaling towards MG. o Outgoing MG: MG initiates the call signaling towards R2 exchange. Laha, Nair Standards Track - Expires September 2003 3 Megaco/H.248 R2 Package Hence as shown in the figure above, MG1 is an incoming MG and MG2 is an outgoing MG. b) The call agent (MGC) is transparent of the transmission details at the physical layer i.e. the R2 terminations at MG are analogue / digital, one-way / both-ways etc. The MG is therefore assumed to be provisioned with the actual signaling frequencies for inter-register signaling (2-out-of-n in-band multi frequency code with forward and backward compelled signaling) along with their properties such as amplitude, tone duration, cadence etc and also their logical significance. All timers that dictate the inter- register compelling actions are also assumed to be provisioned in the MG. c) The MG, behaving as an incoming end, MAY not be provisioned to recognize the "end of pulsing" compelled forward register signal. It is assumed therefore that the incoming MG SHALL detect the end of digit information in called party number based on some digit map. This SHALL also take care of situations where identification of end of digit sequence is through length determination or timeout mechanisms. Calling party number SHALL be compelled till the occurrence of maximum length of calling party number or timeout, specified as package property, or encountering end of pulsing. The MG is assumed to be provisioned with a list of possible country codes. The MG SHALL compel the country code digits based on this provisioned information. d) The VoIP Gateway (MG and MGC), supporting signaling System R2 on the PSTN side, forms the signaling and media interworking gateway between two very different types of signaling and network. It is therefore assumed that the MG SHALL either originate or terminate R2 signaling (acting as a true inter- working unit between the PSTN and packet network both in terms of signaling and media) depending on whether it emulates the outgoing or incoming end in the signal path. Under tandem operation, therefore, the MG converts end-to- end R2 signaling to link-by-link signaling and does not allow R2 register signals to pass through it as tones. 6. R2 Package 6.1 Package Package Name: R2 Package Package ID: r2 (To be allocated through IANA) Description: This package provides package parameters applicable to terminations supporting compelled R2 register signaling between the Media Gateway and the PSTN network. Version: 1 Extends: bcas Laha, Nair Standards Track - Expires September 2003 4 Megaco/H.248 R2 Package 6.2 Properties The MG has a provisioned value for all the properties. If unmodified by MGC, the MG uses the provisioned value by default. Property Name: Source Number Length Property id: snl (0x0001) Description: Indicates that the calling party digits are to be collected By the MG upto a maximum length as specified by this parameter value. Type: integer Possible values: 0 and up Defined in: TerminationState Characteristics: Read/Write Property Name: Compelling Sequence Keepalive Time Property id: cskt (0x0002) Description: Specifies the time duration for which the incoming MG MAY keep alive the compelling sequence, waiting for the subscriber line status information from MGC. Type: integer Possible Values: 0 and up in milliseconds Defined In: TerminationState Characteristics: Read 6.3 Events The actual frequency, cadence, duration and amplitude values for the multi- frequency tones that convey the register signaling information on the physical interface are provisioned in the MG. 6.3.1 Event Name: R2 Address EventID: r2addr (0x0001) Description: Reports the address parameter collected through compelled register signaling. The address parameter include the destination number, source number identification, the calling subscriber category, controlling information for echo suppression, country code, nature of trunk circuit and discriminating digit information for international calls (whichever is compelled and collected). EventsDescriptor Parameters: Digit map parameter activated for collection of destination number, specifying a digit map by name (previously configured) or by value. ObservedEventsDescriptor Parameters: Parameter Name: Destination Number ParameterID: di (0x0001) Laha, Nair Standards Track - Expires September 2003 5 Megaco/H.248 R2 Package Description: The called party number digit string that matched part or all of an alternative sequence specified in the digit map, collected through the compelled register signaling. This is a mandatory ObservedEventsDescriptor parameter. Type: String of digits returned as a quoted string. Possible Values: A sequence of the characters "0" through "9" Parameter Name: Destination Number Termination Method ParameterID: dimeth (0x0002) Description: Indicates the reason for the generation of the Destination number parameter. This is a mandatory ObservedEventsDescriptor parameter. Type: enumeration Possible values: "UM" (0x0001) Unambiguous match "PM" (0x0002) Partial match "FM" (0x0003) Full match Parameter Name: Source Number ParameterID: si (0x0003) Description: If present, reports the compelled calling party number digit string. Type: string of digits returned as a quoted string. Possible Values: a sequence of the characters "0" through "9" Parameter Name: Source Number Termination Method ParameterID: simeth (0x0004) Description: If Source Number parameter is reported, indicates the reason for the generation of the same. Type: enumeration Possible values: "EP" (0x0001) End of Pulsing "ML" (0x0002) Maximum Length "TO" (0x0003) Timeout Parameter Name: Calling Subscriber Category ParameterID: sc (0x0005) Description: If present, reports the compelled calling party subscriber's category. Type: enumeration Possible Values: "NNPS" (0x0001) Non-priority subscriber (National Working) "NPRS" (0x0002) Priority subscriber (National Working) "NMNT" (0x0003) Maintenance equipment (National working) "NOPR" (0x0004) Operator call (National Working) "NDT" (0x0005) Data transmission (National working) "ISOPR" (0x0006) Subscriber or operator without forward transfer facility (International working) Laha, Nair Standards Track - Expires September 2003 6 Megaco/H.248 R2 Package "IOPRF" (0x0007) Operator with forward transfer facility (International working) "IDT" (0x0008) Data transmission (International working) "IPRS" (0x0009) Priority subscriber (International working) "NSMTR" (0x000a) Subscriber with meter (National working) "SIDD" (0x000b) Subscriber with IDD Parameter Name: Echo Suppression Information ParameterID: es (0x0006) Description: If present, conveys the compelled control information on echo suppressors Type: enumeration Possible Values: "OGRQ" (0x0001) Call requires echo suppressors and outgoing half-echo suppressor has to be inserted "NRQ" (0x0002) Call MAY not require any echo suppressor "OGINS" (0x0003) Call requires echo suppressors and outgoing half-echo suppressor has already been inserted "ICRQ" (0x0004) Call requires incoming echo suppressors to be inserted Parameter Name: Country Code Information ParameterID: cc (0x0007) Description: If present, conveys the country code (and possibly the area code) digit string collected as a part of the compelled register signaling in international working. Type: string of digits returned as a quoted string. Possible values: A sequence of the characters "0" through "9" Parameter Name: Discriminating Indicator ParameterID: disc (0x0008) Description: If present, specifies the compelled information on discriminating digit for automatic working. For semi-automatic working this MAY specify the service language (Language digit) to be used by the operator. For international working MAY serve as a test call indicator also. Type: enumeration Possible Values: "DISC"(0x0001) Discriminating digit for automatic working "FR" (0x0002) Language digit French "EN" (0x0003) Language digit English "GR" (0x0004) Language digit German "RU" (0x0005) Language digit Russian Laha, Nair Standards Track - Expires September 2003 7 Megaco/H.248 R2 Package "SP" (0x0006) Language digit Spanish "OT" (0x0007) Language digit Other "TCI" (0x0008) Call by automatic test equipment Parameter Name: Nature of circuit ParameterID: nac (0x0009) Description: If present, reports the compelled information on the nature of circuits involved in the connection so far viz. inclusion of satellite link. Type: enumeration Possible Values: "SATINC" (0x0001) Satellite link included "SATNOINC" (0x0002) Satellite link not included 6.3.2 Event Name: Called Party Reachability Status EventID: cprs (0x0002) Description: Reports the line status of the called subscriber, collected by the outgoing end through compelled register signaling. EventsDescriptor Parameters: none defined by this package ObservedEventsDescriptor Parameters: Parameter Name: Called Party Line Condition ParameterID: cplc (0x0001) Description: Line conditions of the called subscriber Type: enumeration Possible Values: "UN" (0x0001) Unallocated number "SLB" (0x0002) Subscriber line busy "SLFC" (0x0003) Subscriber line free, charge "SLFNOC" (0x0004) Subscriber line free, no charge "SOO" (0x0005) Subscriber out of order "SIT" (0x0006) Send special information tone "NK" (0x0007) Subscriber status not known, set-up speech path 6.3.3 Event Name: R2 Failure EventID: r2f (0x0003) Description: Reports abnormal R2 register signaling conditions to MGC EventsDescriptor Parameters: none defined by this package ObservedEventsDescriptor Parameters: Parameter Name: Error Code ParameterID: ec (0x0001) Description: Describes the failure reason Type: enumeration Laha, Nair Standards Track - Expires September 2003 8 Megaco/H.248 R2 Package Possible Values: "ERR" (0x0001) Error in compelling sequence with peer R2 register "INC" (0x0002) Information signaled by the MGC is incomplete to continue with the compelling sequence at outgoing MG "DISC" (0x0003) Information signaled by the MGC is inappropriate at the compelling stage at MG and hence discarded 6.3.4 Event Name: Destination number EventID: di (0x0004) Description: Event to report destination number address parameter to MGC. EventsDescriptor Parameters: Digit map parameter activated for collection of destination number, specifying a digit map by name (previously configured) or by value. ObservedEventsDescriptor Parameters: Parameter Name: Destination number ParameterID: di (0x0001) Description: The called party number digit string that matched part or all of an alternative sequence specified in the digit map, collected through the compelled register signaling. Type: String of digits returned as a quoted string. Possible Values: A sequence of the characters "0" through "9" Parameter Name: Destination number Termination Method ParameterID: dimeth (0x0002) Description: Indicates the reason for the generation of the Destination number parameter. Type: enumeration Possible values: "UM" (0x0001) Unambiguous match "PM" (0x0002) Partial match "FM" (0x0003) Full match 6.3.5 Event Name: Source number EventID: si (0x0005) Description: Event to report source number address parameter to MGC. EventsDescriptor Parameters: none defined by this package ObservedEventsDescriptor Parameters: Parameter Name: Source number ParameterID: si (0x0001) Laha, Nair Standards Track - Expires September 2003 9 Megaco/H.248 R2 Package Description: Reports the compelled calling party number digit string. Type: String of digits returned as a quoted string. Possible Values: A sequence of the characters "0" through "9" Parameter Name: Source Number Termination Method ParameterID: simeth (0x0002) Description: If Source Number parameter is reported, indicates the reason for the generation of the same. Type: enumeration Possible values: "EP" (0x0001) End of Pulsing "ML" (0x0002) Maximum Length "TO" (0x0003) Timeout 6.3.6 Event Name: Calling Subscriber Category EventID: sc (0x0006) Description: Event to report calling subscriber category parameter to MGC. EventsDescriptor Parameters: none defined by this package ObservedEventsDescriptor Parameters: Parameter Name: Subscriber Category ParameterID: sc (0x0001) Description: Calling Party's category, as collected through compelled register signaling. Type: enumeration Possible Values: "NNPS" (0x0001) Non-priority subscriber (National Working) "NPRS" (0x0002) Priority subscriber (National Working) "NMNT" (0x0003) Maintenance equipment (National working) "NOPR" (0x0004) Operator call (National Working) "NDT" (0x0005) Data transmission (National working) "ISOPR" (0x0006) Subscriber or operator without forward transfer facility (International working) "IOPRF" (0x0007) Operator with forward transfer facility (International working) "IDT" (0x0008) Data transmission (International working) "IPRS" (0x0009) Priority subscriber (International working) "NSMTR" (0x000a) Subscriber with meter (National working) "SIDD" (0x000b) Subscriber with IDD Laha, Nair Standards Track - Expires September 2003 10 Megaco/H.248 R2 Package 6.3.7 Event Name: Echo Suppression Information EventID: es (0x0007) Description: Event to report echo suppression information parameter to MGC. EventsDescriptor Parameters: none defined by this package ObservedEventsDescriptor Parameters: Parameter Name: Echo Suppression Information ParameterID: es (0x0001) Description: Control Information on echo suppressors Type: enumeration Possible Values: "OGRQ" (0x0001) Call requires echo suppressors and outgoing half-echo suppressor has to be inserted "NRQ" (0x0002) Call MAY not require any echo suppressor "OGINS" (0x0003) Call requires echo suppressors and outgoing half-echo suppressor has already been inserted "ICRQ" (0x0004) Call requires incoming echo suppressors to be inserted 6.3.8 Event Name: Country Code Information EventID: cc (0x0008) Description: Event to specify country code information parameter to MGC. EventsDescriptor Parameters: none defined by this package ObservedEventsDescriptor Parameters: Parameter Name: Country Code Information ParameterID: cc (0x0001) Description: Country code (and possibly area code)digit string collected as a part of the compelled register signaling in international working. Type: string of digits returned as a quoted string. Possible values: A sequence of the characters "0" through "9" 6.3.9 Event Name: Discriminating Indicator EventID: disc (0x0009) Description: Event to specify discriminating indicator parameter to MGC. EventsDescriptor Parameters: none defined by this package Laha, Nair Standards Track - Expires September 2003 11 Megaco/H.248 R2 Package ObservedEventsDescriptor Parameters: Parameter Name: Discriminating Indicator ParameterID: disc (0x0001) Description: For automatic working this MAY specify that a discriminating digit is used. For semi- automatic working MAY specify the service language (Language digit) to be used by the operator. For international working MAY serve as a test call indicator. Type: enumeration Possible Values: "DISC"(0x0001) Discriminating digit for automatic working "FR" (0x0002) Language digit French "EN" (0x0003) Language digit English "GR" (0x0004) Language digit German "RU" (0x0005) Language digit Russian "SP" (0x0006) Language digit Spanish "OT" (0x0007) Language digit Other "TCI" (0x0008) Call by automatic test equipment 6.3.10 Event Name: Nature of circuit EventID: nac (0x000A) Description: Event to specify nature of circuit parameter to MGC. EventsDescriptor Parameters: none defined by this package ObservedEventsDescriptor Parameters: Parameter Name: Nature of circuit ParameterID: nac (0x0001) Description: Reports the nature of circuits involved in the connection so far viz. inclusion of satellite link. Type: enumeration Possible Values: "SATINC" (0x0001) Satellite link included "SATNOINC" (0x0002) Satellite link not included 6.3.11 Event Name: Congestion EventID: cng (0x000B) Description: Event to specify network congestion encountered. EventsDescriptor Parameters: none defined by this package ObservedEventsDescriptor Parameters: none defined by this package Laha, Nair Standards Track - Expires September 2003 12 Megaco/H.248 R2 Package 6.4 Signals The actual frequency, cadence, duration and amplitude values for the multi- frequency tones that convey the register signaling information are provisioned in the MG. 6.4.1 Signal Name: R2 Address SignalID: r2addr (0x0001) Description: Composite signal that supplies all the necessary address parameters to start the compelling register signaling at the outgoing MG. All the parameter conveyed in this signal MAY not be actually applied on the termination by the outgoing MG. The MG SHALL transmit only those information that is relevant to the compelling action configured at the MG. Signal Type: (BR) Brief Duration: Provisioned Additional Parameters: Parameter Name: Destination number ParameterID: di (0x0001) Description: The called party number digits. This parameter SHALL be mandatorily present in the Address signal. Type: string of digits Possible Values: a sequence of the characters "0" through "9" Parameter Name: Source number ParameterID: si (0x0002) Description: The calling party number digits. If the source number is not available at the MGC, this parameter MAY be absent in the Address signal. Type: string of digits Possible Values: a sequence of the characters "0" through "9" Parameter Name: Calling Subscriber Category ParameterID: sc (0x0003) Description: Calling party subscriber's category. If the calling subscriber category is not available at the MGC, this parameter MAY be absent in the signal. Type: enumeration Possible Values: "NNPS" (0x0001) Non-priority subscriber (National Working) "NPRS" (0x0002) Priority subscriber (National Working) "NMNT" (0x0003) Maintenance equipment (National working) "NOPR" (0x0004) Operator call (National Working) "NDT" (0x0005) Data transmission (National working) Laha, Nair Standards Track - Expires September 2003 13 Megaco/H.248 R2 Package "ISOPR" (0x0006) Subscriber or operator without forward transfer facility (International working) "IOPRF" (0x0007) Operator with forward transfer facility (International working) "IDT" (0x0008) Data transmission (International working) "IPRS" (0x0009) Priority subscriber (International working) Parameter Name: Echo Suppression Information ParameterID: es (0x0004) Description: Control information on echo suppressors Type: enumeration Possible Values: "OGRQ" (0x0001) Call requires echo suppressors and outgoing half-echo suppressor has to be inserted "NRQ" (0x0002) Call MAY not require any echo suppressor "OGINS" (0x0003) Call requires echo suppressors and outgoing half-echo suppressor has already been inserted "ICRQ" (0x0004) Call requires incoming echo suppressors to be inserted Parameter Name: Country Code Information ParameterID: cc (0x0005) Description: Country code information. If present, conveys the country code (and possibly the area code as well) information digits. Type: string of digits Possible Values: a sequence of the characters "0" through "9" Parameter Name: Discriminating Indicator ParameterID: disc (0x0006) Description: For automatic working MAY specify that a discriminating digit is used. For semi-automatic working MAY specify the service language (Language digit) to be used by the operator. For international working MAY serve as a test call indicator. Type: enumeration Possible Values: "DISC" (0x0001) Discriminating digit for automatic working "FR" (0x0002) Language digit French "EN" (0x0003) Language digit English "GR" (0x0004) Language digit German "RU" (0x0005) Language digit Russian "SP" (0x0006) Language digit Spanish "OT" (0x0007) Language digit Other "TCI" (0x0008) Call by automatic test equipment Laha, Nair Standards Track - Expires September 2003 14 Megaco/H.248 R2 Package Parameter Name: Nature of Circuit ParameterID: nac (0x0007) Description: conveys the nature of circuits involved in the connection so far viz. inclusion of satellite link. Type: Enumeration Possible Values: "SATINC" (0x0001) Satellite link included "SATNOINC" (0x0002) Satellite link not included 6.4.2 Signal Name: Congestion SignalID: cng (0x0002) Description: This signal applies the network congestion compelled R2 signal on a termination in the incoming MG. It arises when at MGC the call setup attempt fails owing to unavailability of resources or encounters network congestion while routing. Signal Type: (BR) Brief Duration: Provisioned Additional Parameters: None 6.4.3 Signal Name: Called Party Reachability Status SignalID: cprs (0x0003) Description: This signal applies the compelled R2 signal that translates to called subscriber line status information. Signal Type: (BR) Brief Duration: Provisioned Additional Parameters: Parameter Name: Called Party Line Condition ParameterID: cplc (0x0001) Description: Line conditions of the called subscriber Type: enumeration Possible Values: "UN" (0x0001) Unallocated number "SLB" (0x0002) Subscriber line busy "SLFC" (0x0003) Subscriber line free, charge "SLFNOC" (0x0004) Subscriber line free, no charge "SOO" (0x0005) Subscriber out of order "SIT" (0x0006) Send special information tone 6.5 Statistics none defined by this package Laha, Nair Standards Track - Expires September 2003 15 Megaco/H.248 R2 Package 7. Procedures 7.1 Termination of Called Party Number digit collection at incoming MG MG SHALL collect called party number digits using the digit map specified by MGC. If the MG is provisioned to recognize the "end of pulsing" register signal, this signal together with the digit map SHALL determine the termination condition of the accumulated digits. During called party number compelling when the MG determines that an unambiguous match has been found with an alternative in the digit map, the MG SHALL report the collected digits with the Destination Number Termination Method set to "Unambiguous Match". This matching criterion MAY also coincide with the reception of the "end of pulsing" signal. Digit collection MAY terminate due to completion by timer expiry or the reception of "end of pulsing" signal when an alternative in the digit map has partially matched. The MG SHALL then report the collected digits with the Destination Number Termination Method set to "Partial Match". Similarly, Digit collection MAY terminate due to completion by timer expiry or the reception of "end of pulsing" signal after one of the alternative in the digit map has fully matched and there are more digits available, the MG SHALL report all the collected digits with the Destination Number Termination Method set to "Full Match". The action taken by the MGC based on the Destination Number Termination Method is left implementation specific. 7.2 Termination of Calling Party Number collection at incoming MG MG SHALL collect calling party number digit string till the occurrence of any of the event mentioned below. If MG is provisioned to recognize the end-of-pulsing signal, calling party number collection MAY terminate due to reception of end-of-pulsing signal. In such a case, MG SHALL report all the collected calling party digits with the Source Number Termination Method set to "End of Pulsing". If the "snl" property is set to a non-zero value, MG collects the calling party number for this maximum number of digits. The MG SHALL report all the collected calling party digits with the Source Number Termination Method set to "Maximum Length". MG MAY also implement a digit timeout mechanism. The timer value is provisioned at the MG and started the moment calling party number compelling starts. If the digit collection terminates due to this timeout, MG SHALL report all the collected calling party digits with the Source Number Termination Method set to "Timeout". Laha, Nair Standards Track - Expires September 2003 16 Megaco/H.248 R2 Package The action taken by the MGC based on of the Source Number Termination Method is implementation specific. 7.3 Termination of Country Code digit collection at incoming MG MG maybe locally provisioned with the list of country codes corresponding to location of the outgoing international R2 register based on which the MG MAY terminate the compelling of the country code digits. 7.4 Termination of Compelling Sequence R2 signaling imposes severe timing constraints on the compelling sequence executed at the MG. The MGC MAY take a finite time to signal the Called Party Reachability Status to the incoming MG after the necessary call setup address information has been compelled and reported to MGC. At this point, the incoming MG MAY o Terminate the compelling sequence o Keep the compelling sequence alive If compelling timings are stringent, the incoming MG MAY terminate the compelling sequence without waiting for the call routing status information (Called Party Reachability Status or Congestion signal) being transmitted by the MGC. The MG SHALL transmit a suitable backward register signal that informs the peer R2 register to setup speech-path. The call routing status cannot be therefore signaled through register signaling. In this case, the MGC MAY instruct the MG to transmit the call routing status as inband call progress tones (out of scope of this package), if call routing tones are not already available inband at the MG. If the compelling timings allow some room for the MG to wait for the call routing status to be signaled, the incoming MG MAY alternately choose to keep the compelling sequence alive within protocol limitations. The MG MAY typically start a timer equal to the duration permitted by the R2 register signaling protocol. If within this time, the MGC signals the Called Party Reachability Status (or Congestion signal), the same is transmitted to the peer R2 register as R2 register signals before completing the compelling sequence. If timeout occurs at MG while waiting for the Called Party Reachability Status or Congestion signal, the MG SHALL terminate the compelling sequence by transmitting a suitable backward register signal that informs the peer R2 register to setup speech path. In either case, if the MGC signals the Called Party Reachability Status or Congestion signal after the MG has terminated the compelling sequence, the MG SHALL respond with an R2 Failure event with Error Code set as DISC. The MGC MAY then choose to re-signal the call routing status as inband call progress tones (out of scope of this package). MGC MAY desire to audit the time window for which the incoming MG keeps alive, before terminating, the compelling sequence; waiting for the call routing status. Based on this time window, MGC MAY decide before hand as to Laha, Nair Standards Track - Expires September 2003 17 Megaco/H.248 R2 Package how to send the routing status information to the MG - as Called Party Reachability Status signal (or Congestion signal) or call routing tones. The Compelling Sequence Keepalive Time property MAY be used for this purpose. A value of zero indicates that the MG immediately terminates the compelling sequence. 8. References [1] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. [2] F. Cuervo, N. Greene, A. Rayhan, C. Huitema, B. Rosen, J. Segers, "Megaco Protocol Version 1.0", RFC 3015, November 2000. [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 [4] V.Bajaj, K.Laha, Bill Foster, Michael Brown, Wendy Bothwell, "Megaco/H.248 Basic CAS Packages", Internet Draft, March 2002. [5] Specifications of Signaling System R2, Q.400 to Q.490, Blue Book, CCITT 9. Author's Addresses Kushanava Laha Hughes Software Systems, Ltd. Gurgaon,Haryana,India. 122015. Ph: (91)-124-2346666. Ext-2226 Email: klaha@hss.hns.com. Vikram Nair Hughes Software Systems, Ltd. Gurgaon,Haryana,India. 122015. Ph: (91)-124-2346666. Ex-1632 Email: vnair@hss.hns.com Full Copyright Statement "Copyright (C) The Internet Society (June,2001). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Laha, Nair Standards Track - Expires September 2003 18 Megaco/H.248 R2 Package Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS 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." Laha, Nair Standards Track - Expires September 2003 19