David.

Thanks a lot for taking the time to explain. I think in my hurry to post I forgot to add details.

Instance 1
Opensips + RTPProxy (Registrar + routing).
Instance 2
Freeswitch (IVR/Conferencing/VoiceMail etc.)

Does that setup make sense? What would be the variables (bind_server_ip, external_rtp_ip, external_sip_ip) be please?

Thanks again.