Need some clarity on regions and audio codec preference lists with CUCM ver 11.5 and 8800 series devices. Without going into too much details we started doing additional testing when we noticed some failed recordings with our call recording server and was due to the server not supporting any codecs with higher bit rates than g711. In the below example I will refer to my regions as A and B.
When testing inter and intra site calling and verifying codecs we noticed that a inter site call between 2 8800 series devices the call was setup with AMR_WB (this is because we have OPUS codec disabled in CUCM). We then did the same test between the same phones but with g722 and iSAC disable on the device side and it then negotiated G729.
G729 is what we want between regions. We do not have a region relationship configured between region A and region B so the regions not listed will all use the system default which is what is set on the service parameter clusterwide for audio codec preference list and maximum audio bit rate. These default service parameters are set to 8kbps for max audio bit rate for interregion and factory low loss for default audio codec preference list between regions. Screenshot attached. So my questions are below and if I need to clarify more information let me know.
- Why would disabling iSAC and G722 on the devices change the codec negotiated for inter-region calls if they both using the system defaults?
- Are codec preference lists invoked with both inter-region calls and intra region calls or just between regions.
- Does the default inter region and intra region audio codec preference lists and default max audio bit rate work together for codec negotiation.
