search for: rfc4317

I receive an INVITE/SDP containing: m=audio 11310 RTP/AVP 3 0 101 which I interpret as gsm, ulaw, rfc2833. and I reply with an OK/SDP containing: m=audio 15884 RTP/AVP 0 3 101 which I interpret as ulaw, gsm, rfc2833. How can I tell which codec was actually used for the call? -- Thanks in advance, ------------------------------------------------------------------------- Steve Edwards

..., rfc2833. >> >> How can I tell which codec was actually used for the call? On Fri, 11 May 2018, Daniel Tryba wrote: > AFAIK this is undetermined. The callee can send either ulaw or gsm, > unless the caller wants to narrow it down to 1 codec, see > https://tools.ietf.org/html/rfc4317#section-2.2 > > Most of the time the callee will pick the first (so in this case ulaw). > But there are media gateways out there that choose g711[au] above "more > complex" codecs regardless order in SDP. My prefer PSTN provider will > always prefer alaw if offered since th...