Announcements
- Jonathan Rosenberg announced the SIMPLE BOF
- Many IDs where announced: dns-gl, sip-app-components, sip-deaf-req,
sip-peer-3pcc, sip-189, sip-replaces, sip-t38callflows
- Henning said 'Please do not include numeric citations, such as "SIP
[1] ..." in abstracts'
- Steve Donovan announced dynamicsoft's test message service.
- last call on ISUP MIME type
- a short thread on the use of Call-IDs devolved into a discussion on its use
for distributed conferencing, and the deprecation of Also.
- Threads on torture tests: consensus was to fix text for test7, deprecate
test10. many commented on Neil Deason's proposed new tests.
Consensus was to be liberal in what you recieve; several of the proposed torture
cases can cause the example error or be handled despite the error. Neil agreed
to modify the example of escaping inside the Request-URI. Anders suggested
additional tests for brackets and parameters in Contact headers. Anders and
Hisham Khartabi commented that according to the bis draft, semicolon-delimited
parameters not included in brackets (< and >) are header-parameters as
opposed to URL parameters. Finally, Ashok Roy suggested adding an IPv6 ;maddr
parameter to a torture test.
- In the thread "What am I doing wrong?", someone was having problems
with a UAC receiving a 180 from a first branch then a 180 and 200 from a second
branch. Consensus was to add a torture test for properly handling tags
from forked calls.
- Henning proposed also using the Alert-Info header as a response header,
instead of implementing Adam Roach's ringback draft
- Another thread on ringback tone devolved into a discussion on 180 w/ early
media vs. 183.
Robert Fairle-Cuninghame summarized the thread consensus best "if a PSTN gateway knows
that the callee is being alerted then it should send a 180 with (or without) SDP.
Otherwise, if the PSTN gateway only knows that inband call progress tones are
being provided by the PSTN network (but not the callee alerting state) then ...
183 is more appropriate."
- M Ranganthan replied to a query for availability of SIP grammars, that an
antlr (grammar for java) version would be available shortly.
- 11/15-11/17 "Jain SIP - Issues": Chris Harris asked a) what kind of
exception an implementation of JAIN SIP should throw if it doesn't like one of
the header values, and b) should an implementation automatically respond to un-parsable
messages, or pass them up to the application. An default class/subclass
approach was suggested with some lazy-parsing. Chris also asked if
overriding equals() is desireable.
11/13-11/17 "Identification Problem"/"Record-Route" : Jo
Hornsby started a thread proposing adding an "original-uri" parameter
to carry the parameters from the original URI lost when rewriting the Request
URI for Record Route processing. Bertil Engelholm proposed a non-backwards
compatible change to Route (that it should act like Via). Billy Biggs enumerated
ways in which a proxy would build the Record-Route, and proposed that RR reflect
the next hop in Route as opposed to the final destination. Sean Olson proposed
using both an maddr and raddr parameter, and claimed there was no clean way to
fix RR and provide backwards compatibility.
11/13-11/14 "SIP End-2-End Security" Tom Tang asked how to do end to
end. Michael Thomas clarified some properties of end2end vs. hopwise
encryption.
11/13 "Gateway and Redirect Number": Pete Kazimier asked how to
translate Q.931 redirected number into SIP. Brian Gracely provided a
pointer to the diversion draft. Hisham Khartabi provided a pointer to a
directory of telephony-related drafts on the main SIP site.
- 11/13 "Possilbe REFER problem": Robert Sparks and Billy Biggs had a
spirited discussion about using Contact as the Request-URI in the Refer-To URI.
Robert noted that the Contact may be in a private name space and hence
unreachable by the UA that receives the REFER; Billy noted that the well known
name may be unavailable in some cases; Robert suggested using the Contact, then
using caller preferences (Accept-Contact=<contact>) if the previous REFER
failed; Billy noted that the previous REFER may fail for reasons other than an
invalid Contact address.
- 11/16-11/18 "ID extension of REFER": Rohan Mahy announced an draft
extension to REFER. Venkatesh commented on some potential uses for the
ongoing status of a REFER. Sean Olson asked if the draft causes different
timing/attempts to solve the retransmission problem (it does not). Sean
asked why 183 was not used, Venkatesh asked why the provisionals aren't simply
forwarded.
- 11/14 "From header to ISUP"/"Redirect server returning new
From": These two threads disucssed the mertis of Reply-To and Also-From
headers.
- 11/14 "Session-time with INFO" Christer Holmberg flogged a
dead horse proposing a new "lite" session timer-like mechanism which
uses INFO.
- the "why does INVITE use a 3-way handshake?" question. Billy Biggs,
Jonathan Rosenberg, and Henning mentioned forking, reliability, and speedy
message delivery. Billy Biggs mentioned that retransmissions are
problematic for REFER (because the REFER can be outstanding for more than 32
seconds). Billy also stated that forking is problematic for SUBSCRIBE and
MESSAGE, with which Jonathan disagreed.
- 11/14 "SIP-H.323 INVITE w/ no media": Michel Maddux asked about
using INVITEs with no media for SIP to H.323 calls. Vladislav Zubarev provided a
pointer to and quotes from http://search.ietf.org/internet-drafts/draft-singh-sip-h323-01.txt
and the bis draft to answer the question.
- 11/13-11/14 "Redirect vs Proxy Server": David Schmidlin asked when
to use a redirect vs. proxy role. Billy Biggs and Jonathan Rosenberg replied on
ease of coding, data hiding, and control of the two roles.
11/17 "SDP coder negotiation": Duke Snyder asked about the behavior of
codec negotiation. Billy Biggs and Simon Barber replied with the correct
behavior. Simon asked for a survey of implementations of many of the implied SDP
behaviors.
- contiguous CSeq: bis 6.20 says CSeq number must be contiguous. (insert
"within a transaction")
- what is the "MD5-sess" algorithm in Digest authentication? (clarify
reference)
- can I include both "proxy" and "redirect" in
Request-Disposition? (no)
- does CANCEL of a REFER, cancel the referred INVITE? (yes)