ITSPs

Our Internet Telephony Service Provider (ITSP) will send the calls incoming from DID numbers to us on our "external" SIP profile (port 5080 in demo configuration) .
We will send to the ITSP outbound calls in need of a SIP routing to the external world, using the "external" SIP profile. In dialplan we will use a SIP "gateway" syntax that refers to the authentication needed by our ITSP to accept our outbound traffic.