Summary:ASTERISK-20835: RTP not modified when UAS responds with an OK(200) with other ptime then 20ms
Reporter:not here (looserouting)Labels:
Date Opened:2012-12-21 05:14:48.000-0600Date Closed:2013-01-14 16:16:01.000-0600
Versions:10.11.0 Frequency of
duplicatesASTERISK-20650 Asterisk resets ptime value in 200 OK response
Environment:Attachments:( 0) debug
( 1) extensions.conf
( 2) sip_and_rtp.pcap
( 3) sip.conf
Description:my Asterisk 10 svn recievs an INVITE from A with ptime:20 and invites B also with ptime:20.
now B sends an OK with ptime:30. The OK from Asterisk to A contains ptime:20.
But now the RTP stream from asterisk to A is the same as from B to asterisk. That means asterisk doesn't change the stream ( 20 40 20 40 20 40 )and is transmitting with a ptime of 30ms (30 30 30 30 30 ).
regarding the RFC this shouldn't be an issiue since RFC4566 says:"

It should not be necessary to know ptime to decode RTP
        or vat audio, and it is intended as a recommendation for the
        encoding/packetisation of audio."

but this can lead to strange behaviour of A like synchronisations problems.
Comments:By: Michael L. Young (elguero) 2012-12-21 16:12:34.670-0600

We require a complete debug log to help triage the issue. This document will provide instructions on how to collect debugging logs from an Asterisk machine for the purpose of helping bug marshals troubleshoot an issue: https://wiki.asterisk.org/wiki/display/AST/Collecting+Debug+Information

Also, a pcap would be helpful as well.

By: not here (looserouting) 2012-12-23 10:38:29.405-0600

the debug log is a bit long. It contains the asterisk start and the test call. Nothing else.

the pcap has all the related traffic.
All magic happened on the same machine.

"A" is a softphone (sflpohne). running sip on 35060
"B" is SIPp. I used it to reproduce the Szenario. It first happend with an AVM Fritzbox. 'cause It uses always ptime 30. here running on port 15060
Asterisk itselft is running on port 25060

you' ll also see all 4 streams in the pcap
A to asterisk
asterisk to A
asterisk to B
B to asterisk

By: Matt Jordan (mjordan) 2013-01-14 16:16:01.231-0600

Closing out as a duplicate of ASTERISK-20650.