[Linphone-developers] issue with SDP media attributes in linphone 0.9.0pre3-1

[Alfred E. Heggestad]

Hi

We are developing a low-cost SIP solution running on
a Ubicom microcontroller and we are currently using
linphone for testing. We are using libosip 0.8.8-1
and linphone 0.9.0pre3-1, both Debian packages
from linphone.org

Calling from linphone to our device works fine, but
calling linphone gives a 415 Unsupported Media Type
on our phone. The SDP media attributes we send look
like this:

m=audio 5004 RTP/AV P 0 8
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000

I noticed that linphone sends this:

a=rtpmap:0 mulaw/8000/1
a=rtpmap:8 alaw/8000/1

Is this correct? I suspect that since linphone sends
the mulaw/alaw string it will also expect it for
incoming SDP messages, but I also noticed in oRTP/src/avprofile.c:

PayloadType pcmu8000={
        PAYLOAD_AUDIO_CONTINUOUS,
        8000,
        1.0,
        &offset127,
        1,
        64000,
        "PCMU/8000/1"
};

Does linphone support static and/or dynamic payload types?
Do you know which RFC describes the strings in the SDP
attributes? (it is not the SDP rfc...)

I also tested linphone <--> kphone with the same results.

Btw, if you want use our SIP proxy server you are welcome
to register at sip:sip.sxdesign.com:5060
(try also 193.216.185.60 if above does not work)
We also have a phone at sip:address@hidden
if you would like to test it.
(NOTE: it is still beta but should do basic stuff)


best regards,

Alfred E. Heggestad
SX Design, Norway