Home » Cisco » 350-801 v.2 » Which codec is negotiated when the SDP offer includes this line of text?
A Cisco IP Phone 7841 that is registered to a Cisco UCM with default configuration receives a call setup message. Which codec is negotiated when the SDP offer includes this line of text? m=audio 49181 RTP/AVP 0 8 97
A. G.711alaw
B. iLBC
C. G.722
D. G.711ulaw
Correct Answer: D
Explanation/Reference:
Those are the codecs.
They are RTP payload types, and in preference order.
Eg 8=g711alaw, 0=g711ulaw, 18=g729, 97=this one is special, it’s actually what they want to Mark RTP-NTP (RFC2833) DTMF relay as.
Reference: https://community.cisco.com/t5/ip-telephony-and-phones/sip-sdp-no-codec-specifed/td-p/3913990 https://en.m.wikipedia.org/wiki/RTP_payload_formats
