[Serusers] AW: Snom phone (fwd) more fromn greg fausak
stredicke at snom.de
Tue Mar 4 08:51:09 CET 2003
ooppss that actually changes the scene. Maybe it was too late for me
last night already
You are right, the 200 Ok goes to the PRACK and the
phone mixes that up. I changed it in the phone code and that will be
part of the next release.
Von: Robert Messer [mailto:rmesser at abpintl.com]
Gesendet: Dienstag, 4. März 2003 02:25
An: cs at snom.de
Betreff: FW: Snom phone (fwd) more fromn greg fausak
FYI More from greg
ABP International, Inc.
snom technology - VoIP Phones
From: Greg Fausak [mailto:greg at august.net]
Sent: Monday, March 03, 2003 6:13 PM
Cc: 'Robert Messer'; sip at august.net; serusers at lists.iptel.org
Subject: RE: Snom phone (fwd)
I initially sent the packet:
> > > This is that packet that came from the last 200 OK <- PROXY:
> > >
> > > #
> > > U 2003/02/24 07:56:52.503535 188.8.131.52:5060 ->
> > 184.108.40.206:5060
> > > SIP/2.0 200 OK.
> > > Via: SIP/2.0/UDP 220.127.116.11:5060;branch=z9hG4bK-ng5tokyx448r.
> > > From: "snom man" <sip:4695461245 at augustvoice.net>;tag=8u6ju8wxuc.
> > > To: <sip:2143357976 at augustvoice.net;user=phone>;tag=3CBB0360-532.
> > > Date: Mon, 24 Feb 2003 13:56:43 GMT.
> > > Call-ID: 3c267202b6a8-lgseu8olovlp at 18.104.22.168.
> > > Server: Cisco-SIPGateway/IOS-12.x.
> > > CSeq: 2 INVITE.
> > > Session-Expires: 7200;refresher=uac.
> > > Require: timer.
> > > Allow-Events: telephone-event.
> > > Contact: <sip:92143357976 at 22.214.171.124:5060;user=phone>.
> > > Record-Route: <sip:2143357976 at 126.96.36.199;ftag=8u6ju8wxuc;lr>.
> > > Content-Type: application/sdp.
> > > Content-Length: 209.
> > > .
> > > v=0.
> > > o=CiscoSystemsSIP-GW-UserAgent 7543 5694 IN IP4 188.8.131.52.
> > > s=SIP Call.
> > > c=IN IP4 184.108.40.206.
> > > t=0 0.
> > > m=audio 16632 RTP/AVP 0 100.
> > > a=rtpmap:0 PCMU/8000.
> > > a=rtpmap:100 X-NSE/8000.
> > > a=fmtp:100 192-194.
> > >
This is the 200 OK (response to the INVITE) message as delivered to the
I couldn't figure out what you were saying, so I went back to
the ethereal trace. After the snom phone receives a 183 status
message, it sends a PRACK to the PROXY. This PRACK is
OKed, without a Record-route. The next message is an OK
responding to the original INVITE, which does indeed have a
So, you are saying that the OK to your PRACK needs a record route?
I can do that I think, because the OK to the INVITE does indeed have
I don't even know what a PRACK is for...
From: Kevin [mailto:kmoroz at abpintl.com]
Sent: Monday, March 03, 2003 5:19 PM
To: Greg Fausak
Cc: 'Robert Messer'
Subject: FW: Snom phone (fwd)
Sorry it took so long to get back to you. Normally it is faster but
as I stated the SIP inter-
operability was last week which caused the delay. Looks like the issue
is with the
SER proxy. If I knew the specification deeper I should have been able
to answer it myself. Engineering ccs Jiri on their response to me so
he is aware of the issue.
The phone updates the route until it receives a 2xx code. The 200 Ok
response does not contain such a route therefore the phone uses the last
route it receives in the 200 which is empty. Therefore, the phone MUST
send the ACK directly to the gateway.
§ 12.1.2 of the RFC3261. The dialog is NOT established by the
The proxy can very easily solve the problem by putting itself into the
routing path of the 200 Ok.
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