Create new Audio Codec Preference List by navigating to Cisco Unified CM Administration > System > Region Information > Audio Codec Preference List.

The Maximum Audio Bit rate is still applied for calls within a region and between regions, but rather that using the highest audio quality codec the codec selection is now made based on the codec order in the Audio Codec Preference List and the codecs that the endpoints support. New parameter has been introduced which is Audio Codec Preference Lists. You can also change this on SIP trunk if MTP is selected by changing the parameter MTP Preferred Originating Codec. Note: Within G711 you can choose between alaw or ulaw by changing the service parameters G.711 A-Law Codec Enabled & G.711 Mu-Law Enabled. In Summary CUCM codec selection is based on Best Quality which fits within the configure Max Audio Bit Rate.

CUCM will never advertise G729 for this call, although it has bit rate of 8kbps which is lower than configured max audio bit rate, even if it requested by the other party (in this case xcoder will be deployed or call will fail). If the enterprise service parameter is disabled, CUCM will advertise G.711. For example, if the max audio bit rate configured is 64 kbps (G.722, G.711) & advertise G.722 Codec enterprise parameter is enabled, CUCM will advertise G.722 for this call. CUCM will check the regions for originating and destination endpoints and, accordingly, allocate the configure inter-region/intra-region codec.ĬUCM will apply the codec based on Max Audio Bit Rate.

In CUCM codec selection is based on regions.

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