Hi All, I'm sure I've discussed this before, but I searched through my gmail and google and couldn't find the answer. Below is the SDP parameters from my sip provider. Is it mandatory to always include the rtpmap details for PCMU/PCMA codes? For example something like 'a=rtpmap:8 PCMA/8000' and 'a=rtpmap:0 PCMU/8000'? I'm using sipdroid on android and it rejects this with 'codec not supported' Thanks o=Sippy 141730476 0 IN IP4 xxx.xxx.xxx.xxx s=- t=0 0 m=audio 47676 RTP/AVP 8 0 18 101 c=IN IP4 xxx.xxx.xxx.xxx a=fmtp:18 annexb=yes a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-15 a=sqn: 0 a=cdsc: 1 audio RTP/AVP 8 a=cdsc: 2 image udptl t38 a=cpar: a=T38FaxUdpEC:t38UDPRedundancy a=cpar: a=T38FaxVersion:0 a=cpar: a=T38MaxBitRate:14400 ]