[asterisk-bugs] [JIRA] (ASTERISK-22076) Investigate PJMEDIA's implicit codec negotiation behavior

[Rusty Newton (JIRA)]

Rusty Newton created ASTERISK-22076:
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             Summary: Investigate PJMEDIA's implicit codec negotiation behavior
                 Key: ASTERISK-22076
                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-22076
             Project: Asterisk
          Issue Type: Bug
      Security Level: None
          Components: Channels/chan_gulp
    Affects Versions: 12
            Reporter: Mark Michelson


While attempting to make an equivalent option to chan_sip's preferred_codec_only, I ran across interesting behavior in chan_gulp. I configured two peers, carol and bob. carol is configured to allow=g722,ulaw,alaw. bob is configured to allow=ulaw. Direct media is not enabled.

Carol places a call to Bob through Asterisk. Carol's INVITE contains an SDP offer with ulaw, alaw, g.722, and other codecs. Asterisk sends an INVITE to bob that contains only a ulaw offer. Bob's phone replies with a 200 OK with a ulaw answer. Asterisk then sends a 200 OK with an SDP answer for Carol that contains only g.722. If I change the order of the allow statement for Carol to be allow=ulaw,g722,alaw, then in the same situation, the SDP in the 200 OK from Asterisk to carol contains only ulaw.