PSTN and Internet Internetworking BOF (pint)

Minutes of the PSTN and Internet Interworking (PINT) BOF 

Reported by: I. Faynberg, Bell Labs/Lucent Technologies <>

H. Lu, Bell Labs/Lucent Technologies <> 

The PSTN and Internet Interworking (PINT) BOF meeting took place from 21:00 to 22:00 on Wednesday, April 9. The meeting was chaired by Igor Faynberg (Bell Labs/Lucent Technologies) and co-chaired by Hui-Lan Lu (same organization) who also took minutes. Ninety people attended the meeting. 

The goal of the meeting was to discuss two internet drafts: 

1. Draft-faynberg-telephone-sw-net-00.txt - describing an Internet/PSTN connection arrangement through which combined Web and traditional telephony services can be delivered. 

2. Draft-zigmond-media-url-00.txt - describing an URL scheme for telephony. 

Murali Krishnaswamy, Bell Labs, led the discussion of Item #1, and the presentation summarized the relevant internet draft. The questions asked entered around the following issues: 

The services supported with the proposed arrangement and what types of servers would be connected to the PSTN. 

Answer: A combination of traditional internet and telephony services. A specific example is Web-based Yellow Pages services, for which a Web server would be connected to the PSTN. 

Why canít the Switch/Computer Application Interface (SCAI) platform be used? 

Answer: It can. In fact, it is very similar to IN (the proposed means of accessing the network), and the protocol used for accessing IN could be used for accessing the SCAI architecture. The IN arrangement, however, is more powerful because IN controls the whole network, while the SCAI application controls a single switch. 

Why canít the client place the call? 

Answer: It can, of course. However, unless the client is to pay for the call, which is contrary to the assumption about the types of services, the IN will have to take care of it (e.g., the 800 number) eventually. It is much better to take care of it sooner--and right in the middle of the network rather than at the end point. It also allows the network to optimize its resources. 

How does this proposal relate to packet voice? 

Answer: It does not. 

However, should we not work in this group on the interconnections between the IP routers and PSTN in order to deliver packet voice across the Internet/PSTN boundaries? 

Answer: Perhaps we should. However, there is no group yet and no draft on the table today; therefore, we cannot discuss this kind of interconnection right now. 

How can the call be placed to the user if user's line is already occupied [by the Internet connection]? 

Answer: The proposal is meaningful only with the use of an ISDN connection, a voice and data modem, a digital subscriber line, or some other arrangement (e.g., two voice lines), which leaves place for a voice call. 

So, what are the protocols to be standardized? 

Answer: There are two protocols. [As the proposal says:] The TCP/IP-based protocol between the server and Service Node (or Service Control Point), and the SMNP-based protocol between the router and the Service Management System. 

At the end of a half-an-hour discussion, a large number of participants expressed support for carrying out the work in the IETF, but there was also a sizable opposition to the proposal. It was agreed to continue the discussion via e-mail. The self-subscribing e-mail discussion list was to be created by I. Faynberg and announced by the IETF. [At the time of publication of these notes, the list has been created:] 

Dan Zigmond, Wink Technologies, led the discussion of Item #2. Dan has introduced his proposal for the URL format for telephony. The following questions were asked: 

Is the addressing scheme relative or absolute? 

Answer: According to the design, it could be either. [A suggestion from the audience was that since the proposed addressing follows the design of the "mail-to" addressing, it should support be absolute.] 

Where will this type of URL be used? 

Answer: Click-to-dial, automatic billing, for example. 

It should be useful to specify--within the proposed schemeóthe attributes for the post-dialing delay, PIN, time to call, and the type of the phone (e.g., cellular). 

Answer: Yes, that could be done. 

Why not simply use the telephone number as is? Why URL? 

Answer: To be able to process things in a pre-set way (i.e., have the attributes as discussed in 3). 

The meeting expressed strong support for carrying out the work. It is felt that the proposed work item is too small to warrant a separate working group. The discussion leading to a standard will continue via e-mail. The self-subscribing e-mail discussion list will be created by D. Zigmond (please send requests to and announced by the IETF. 


1. PSTN/Internet Internetworking Agenda