Codecs configuration
Codecs iLBC, iSAC, L16 and AAC-LD should be disabled for Recording-Enabled devices as they are not supported by MiaRec recording system at the moment.
Use the System > Service Parameters menu option in Cisco Unified Communications Manager Administration to perform the necessary configuration.
Change the following settings of group Clusterwide Parameters (System - Location and Region):
- iLBC Codec Enabled to Enabled for All Devices Except Recording-Enabled Devices
- iSAC Codec Enabled to Enabled for All Devices Except Recording-Enabled Devices
- Default Intraregion Max Audio Bit Rate to 64 kbps (G.722, G.711)
Disable 256kpbs wideband codec
Latest models of Cisco phones support high quality 256kbps wideband codec for phone-to-phone communications withing the same region. Unfortunately, this codec is not supported by Cisco Built-in-Bridge recording method and it should be disabled otherwise internal calls between users will not be recorded.
Navigate to the System > Region menu option in Cisco Unified Communications Manager Administration and change per-region setting Max Audio Bit Rate to either Use System Default or 64 kbps (G.722, G.711) as shown in below screenshot.
Recording of conference calls
Recording of conference calls on Cisco platform has the following limitations:
- Cisco UCM doesn't support re-negotiated of audio codecs for calls which are recorded with Built-in-Bridge method.
- The Cisco Software Conference Bridge supports only G.711 and 256k wideband codecs.
The following call scenario may occur:
- One user makes a call to another user. If these two users use Cisco phones, then G.722 wideband codec is chosen for such call.
- Then one of users tries to create a 3-way conference and add the third user to the conference.
- CUCM creates a software-based conference to mix audio from three users. The software-based conference doesn’t support G.722 codec.
- CUCM needs to re-negotiate codec with each of users and change it from G.722 to G.711.
- But CUCM cannot do that because such call is recorded with BiB method and codec is fixed for such call.
- As a result a user, who tries to create a conference is dropped from a conference.
There are two workarounds for this situation:
Disable G.722 codec for users, which are recorded with BiB method.
Allocate codec transcoding resources on Cisco platform to automatically convert audio from one codec to another on-flight.
To disable G.722 codec, change the setting G.722 Codec Enabled to Enabled for All Devices Except Recording-Enabled Devices.
