This example explains how you can configure the OCSBC and applicable resources to support calls between EVS and AMR-WB endpoints without requiring transcoding, and therefore not consuming OCSBC transcoding resources. This use case, established by logic within the OCSBC, can accommodate calls in either direction.

In this call flow a codec policy is set on the egress realm to not allow AMR-WB and to add EVS AMR-WB IO on egress. The offer contains AMR-WB. The OCSBC recognizes that the incoming AMR-WB codec matches the EVS codec to be added:

• They have the same octet-align
• EVS codec is in interoperable mode (evs-mode-switch=1)
• You have a media-profile configured that matches the parameters presented in the AMR-WB offer

The OCSBC strips AMR-WB and adds EVS with the same payload type as AMR-WB even though EVS is not configured with that payload type.

codec-policy
name Transparent-AMR-WB-IO
allow-codecs * AMR-WB:no
add-codecs-on-egress EVS::WBIO
force-ptime disabled 

The call proceeds transparently between AMR-WB and EVS.