Starting with ITSPB/SP2 settings at Default, a minimal configuration would be:
Service Providers -> ITSP Profile B -> SIP -> ProxyServer : (Callcentric Proxy Server)
Voice Services -> SP2 Service -> X_ServProvProfile : B
Voice Services -> SP2 Service -> AuthUserName : (Callcentric Username)
Voice Services -> SP2 Service -> AuthPassword : (Callcentric Password)