CM 6 Evolution Server: Codec selection

[ahartoch]

Hi,

I would like somebody to help me understand how is the codec selection on an evolution or feature server environment. Do SIP phones follow the same criteria as H323 phones with regards Codec Selection and Network Regions?

Regards
Alex

[zhuayong]

Hi Alex,

In case of CM-ES or CM-FS, you will register SIP phones to ASM, which known as OPTIM phones. NR and Codec are concepts inside CM that can be applied to H323 phones whereas SIP phones are actually registered on ASM and ASM/SMGR defines the codec/bandwidth parameters for SIP phones. You know that normally we define a H323 IP phone's NR/Codec by referring to either its CLAN or IP-Network-Map form, SIP Phones simply don't register on CM therefore SIP phones and H323 phones are different in that regards.

On ASM we have home location concept wherein you can administer the overall bandwidth as well as per call bandwidth in a format of kbit/sec rather than G711 or G729 etc. But in general, 83k for G711(20ms) and 27k for G729.

However, you still utilize the NR and ip-codec-set while administering the signaling group between CM-ES/CM-FS and ASM. But, that's meant for CM and ASM communications not for SIP phones.

Hope this clarifies a bit.

Regards,
Howard

[zhuayong]

Hi Alex,

I would like to make a correction.

Base on the lab testing result, when SIP phone places an outbound call, its NR/Codec will be derived from the "Far-end Network Region" form of corresponding SIP Signaling Group, if CM-FS is used with SM. That said, CM-FS will be controlling the codec selection for such scenarios.

If CM-FS is not used for SIP phone then the home location administered for that user will be considered.