For starters, query the vendor for the following - 1. IP addresses to use. Public IP for the vendor which will receive and respond to requests from CME. 2. Will the SIP trunk require Registration ? If yes, credentials and registrar information. 3. Will proxy authentication be required ? If yes, credentials/authentication information need to be shared. 4. Will they support 302/Refer for call forwarding/transfers ? If not, disable them to avoid call failure in these scenarios.
