Modify Fax Relay Profile B
From TBwiki
To configure NSE, you must go in your profile.
You simply have to check "Use NSE", like:
If NSE exchange is possible (negociated in the SDP), the switch to passthrough will happen in the RTP stream, not with a SIP re-INVITE anymore.
Note:
Our implementation of NSE currently only support switch to passthrough, which means you can exchange NSE packets to switch to T.38.