A Cisco IP Phone 7841 that is registered to a Cisco Unified Communications Manager with default configuration receives a call setup message. Which codec is negotiated when the SDP offer includes…

The correct answer is A. G.711ulaw. 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…

Protocols and Endpoints

Question

A Cisco IP Phone 7841 that is registered to a Cisco Unified Communications Manager with default configuration receives a call setup message. Which codec is negotiated when the SDP offer includes this line of text? M=audio 498181 RTP/AVP 0 8 97

Options

AG.711ulaw
BiLBC
CG.711alaw
DG.722

How the community answered

(30 responses)

A
90% (27)
B
3% (1)
C
7% (2)

Explanation

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. 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

Topics

#SDP#Codecs#RTP Payload Types#CUCM Call Flow

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