Minutes of the PSTN/Internet Interworking (pint) WG
Meeting on December 10, 1997
Reported by
S. Bellovin (AT&T Labs-Research) smb@research.att.com and
I. Faynberg (Bell Labs, Lucent Technologies) faynberg@bell-labs.com,
based on the notes taken by Hui-Lan Lu (Bell Labs).
The PSTN/Internet Interworking (PINT) WG meeting took
place from 19 :30 to 22:00 on Wednesday, December 10. The meeting was chaired
by Steve Bellovin (ATT Labs-Research) and Igor Faynberg (Bell Labs/Lucent
Technologies). The WG roster registers 155 attendees.
Hui-Lan Lu, to whom many thanks, took notes and helped to prepare this
report.
The proposed agenda of the meeting was as follows:
1. 19:30-19:35 Chairs Agenda bashing
2. 19.35-19:55 L. Conroy Pre-PINT Service Implementation Experiences
3. 19:55-20:10 M. Krishnaswamy Pre-PINT Implementation Report
4. 20:10-20:35 S. Petrack IP Access to PSTN Services:
Basic Service Requirements,
Definitions, and Architecture
5. 20:35-20:55 H. Schulzrinne SIP for Click-to-Dial-Back and
Third-Party Control
6. 20:55-21:10 S. Bellovin On Security Requirements for PINT
7. 21:10-21:30 P. Davidson A Proposal for a Simple Computer Telephony
Protocol
8. 21:30-21:45 F. Burg An Architecture and Protocols for Initiation
and Control of Telephone Calls From Terminals
Connected to a CallBroker over a TCP/IP
Connection.
9. 21:45-21:55 Hui-Lan Lu Putting together an Informational RFC
10. 21:55-22:00 Chairs Work items for the next quarter
11. 22:00 All Adjourn
During the discussion of item (1) it was proposed and agreed to present item (6)
ahead of item (4). In addition, item (8) was moved ahead of item (6), and
Tony DeSimone (AT&T) was named its presenter. It was also announced that
after the meeting Fred Burg would give a demo supporting the presentation.
Item (2) presented the Siemens pre-PINT implementation experiences as proposed
for the Informational RFC. Responding to questions, Lawrence Conroy pointed
out that the ITU-T CS-1 INAP was used in the prototype and that the protocol
with the gateway was service-independent. There was no disagreement with
the presented material.
Item (3) presented the Lucent pre-PINT implementation experiences, as proposed
for the Informational RFC. Murali Krishnaswamy announced that part
of his draft summarized the material that had already been
presented to PINT, for which reason his presentation was focused on the
new aspect: the structure of Management Information Base (MIB), which he
had implemented. Responding to questions, Murali explained that the
SMS role was to provision the service logic to the service node, and that
the Service Data Function (SDF) was implemented as part of the service node.
There was no disagreement with the presented material.
Item (4) presented the proposed terminology and service requirements (and
scenarios) destined for the future standards-track RFC. Scott Petrack
clarified, in response to questions, that a) the word "terminal" refers to
telephone terminals (not IP hosts) and b) PINT Clients and PINT Servers are
IP hosts. There were no disagreements, but two concerns were expressed:
1) The issue of potential overlapping of authorization domains
2) Some services (like conference calling) that rely on the call-
control-related features that are outside the present PINT
charter.
The first issue has been taken off-line; it will be resolved in consultation
with the Area Directors. As far as the second issue is concerned, both
chairmen re-affirmed that only the charter-related material is relevant
to the meeting; the rest of it, although of high quality and interest
to others, will be retained in waiting until the present charter has been
completed.
Item 8 (presented by Tony DeSimone of AT&T) shared a company
experience with the implementation of "click-to-dial-back" service.
This presentation was unique in that it demonstrated relevant API.
This has raised a question of whether AT&T had patents related to
the subject. All members of the working group were referred to
RFC 2026. Briefly, working groups are free to adopt patent-encumbered
technology; however, the patent owners must agree to license the
patents on reasonable and non-discriminatory terms. Furthermore,
anyone who submits a mechanism that may be protected is obligated
to disclose any encumberances he or she is aware of. Finally,
anyone and everyone is invited to make the IESG aware of any patents
pertaining to any standards-track RFC. In response to other
questions, Tony pointed out the interface between the call broker
and the switch is a) IP-based, b) reflects the client-server model,
and c) in the current implementation, the call broker resides in
the telecom server domain (not in the Internet domain).
Item 6 presented security requirements for PINT. There were no objections and no
questions.
Item 5 demonstrated the use of SIP (which is, the protocol of choice for
PINT) for supporting click-to-dial-back and other PINT services. In response
to a suggestion to have more flexible SDP for passing call-related information,
Henning invited contributions on this topic.
Item 7 presented SCTP to start a discussion on how this protocol fits within
PINT. During the discussion it was noted that the SCTP is a feature-rich
CTI protocol that can serve well as the transport mechanism supporting various
APIs (e.g., S.100, TSAPI, and JTAPI). A concern was expressed whether the
SCTP would be appropriate for the Internet. To address this concern, Paul
mentioned that the SCTP, just in order to be useful for the Internet, has been
based on the HTTP. The other concern, which still remains open, is how
exactly the SCTP can be used to support PINT services efficiently.
Item 9 presented the outline of the Informational RFC (no disagreement)
and expressed the editor's intention to complete the draft by the
end of January.
The chairmen thanked the presenters and audience for active, cheerful
and cooperative participation, thanks to which an unusually large agenda
was covered. The PINT participants were asked to request their time
slots for future meetings before the dead-line so that sufficient
meeting time be scheduled.