CMR - Codec Mode Request

The CMR is part of the RTP (Real time Transport Protocol) Payload Header which is used in the transportation of AMR (Adaptive Multi Rate) speech samples. The CMR field is used to indicate to the receiver of the RTP stream how the transmitter wishes future speech frames to be encoded. This may typically be sent from a wireless gateway, interfacing with a mobile network.


  • Fully interactive 3GPP based network map
  • Narrated call flows
  • Detailed network procedures

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