If you're still having problems, these settings work reliably for me.
For Callcentric on SP1:
Service Providers -> ITSP Profile A -> General -> Name : Callcentric
Service Providers -> ITSP Profile A -> General -> DigitMap:
(<'S'B:**275*>xx.|*123|<**275*:SB>xx.|[2-9]11S0|<1aaa>[2-9]xxxxxx|<1>[2-9]xxxxxxxxx|
1xxxxxxxxxx|011xx.|(Mipd)|[^*#]@@.'@'@@.)
where aaa is your local area code.
Service Providers -> ITSP Profile A -> SIP -> ProxyServer :
callcentric.comService Providers -> ITSP Profile A -> SIP -> OutboundProxy :
callcentric.comService Providers -> ITSP Profile A -> SIP -> RegistrationPeriod : 3600
Voice Services -> SP1 Service -> X_ServProvProfile : A
Voice Services -> SP1 Service -> AuthUserName : 1777nnnnnnn
Voice Services -> SP1 Service -> AuthPassword : (sip password)
Voice Services -> SP1 Service -> CallerIDName : (callerid name)
Voice Services -> SP1 Service -> MWIEnable : (checked)
Voice Services -> SP1 Service -> X_VMWIEnable : (checked)
Voice Services -> SP1 Service -> MessageWaiting : (unchecked) (Default unchecked)
For Callcentric on SP2:
Service Providers -> ITSP Profile B -> General -> Name : Callcentric
Service Providers -> ITSP Profile B -> General -> DigitMap:
(<'S'B:**275*>xx.|*123|<**275*:SB>xx.|[2-9]11S0|<1aaa>[2-9]xxxxxx|<1>[2-9]xxxxxxxxx|
1xxxxxxxxxx|011xx.|(Mipd)|[^*#]@@.'@'@@.)
where aaa is your local area code.
Service Providers -> ITSP Profile B -> SIP -> ProxyServer :
callcentric.comService Providers -> ITSP Profile B -> SIP -> OutboundProxy :
callcentric.comService Providers -> ITSP Profile B -> SIP -> RegistrationPeriod : 3600
Voice Services -> SP2 Service -> X_ServProvProfile : B
Voice Services -> SP2 Service -> AuthUserName : 1777nnnnnnn
Voice Services -> SP2 Service -> AuthPassword : (sip password)
Voice Services -> SP2 Service -> CallerIDName : (callerid name)
Voice Services -> SP2 Service -> MWIEnable : (checked)
Voice Services -> SP2 Service -> X_VMWIEnable : (checked)
Voice Services -> SP2 Service -> MessageWaiting : (unchecked) (Default unchecked)