mod_sangoma_codec enables FreeSWITCH to use Sangoma Transcoding cards.
You first need to install the Sangoma transcoding software. see http://wiki.sangoma.com/Sangoma-Media-Transcoding for instructions.
Handling media reinvites
mod_sangoma_codec does not play a role in SIP signalling codec negotiation, this is still handled by FreeSWITCH. In particular if you need to change codecs on reINVITE, you need to enable this parameter Variable_sip_renegotiate_codec_on_reinvite
Monitoring Sangoma license utilisation
There is currently no way to get a definitive count of the active number of licensed sessions consumed by the card. The only command which can give you any insight is the console command "sangoma_codec sessions".
When you issue the console command "sangoma_codec sessions" you will most likely get a list of sessions which shows one session with an encoder and another session with a decoder. According to Sangoma technical support, although two sessions are shown for a single transcoded leg, this appears as two sessions in "sangoma_codec sessions" yet only consumed one licensed transcoding session. Providing you are only transcoding between one codec registered with mod_sangoma_codec and one codec managed by FreeSWITCH internally, you will only use one Sangoma transcoding session.
Any sessions which show neither an encoder or decoder in use do not count against any licensed usage.