Quality Management Suite

Cisco Forked Audio -  SIP Phone Codec

1.    SIP phone programs have the ability to select a non-standard codec to use in place of codec's configured elsewhere in Cisco Call Manager.  In the illustration below, checkout the options for the iLBC (Internet Low Bit Rate Codec)  and iSAC (Internet Speech Audio Codec) Codec's.  These need to be disabled.  

2.    This option is relatively new in Cisco and allows the SIP phones to decide on their own, when talking to another equally capable SIP phone, to bypass their configuration and employ either the iLBC or iSAC Codec. We actually encountered this problem at a customer site and with the help of Cisco Tac, tracked this problem down.