Assuming you want to put RingCentral on SP1/ITSPA, the following minimal configuration should get you going starting with everything set at Default:
Service Providers -> ITSP Profile A -> General -> Name : RingCentral
Service Providers -> ITSP Profile A -> SIP -> ProxyServer :
sip.ringcentral.comService Providers -> ITSP Profile A -> SIP -> OutboundProxy : (if required)
Voice Services -> SP1 -> AuthUserName : (your assigned username)
Voice Services -> SP1 -> AuthPassword : (your assigned password)
Voice Services -> SP1 -> CallerIDName : RALSTON CONSULTING INC
Physical Interfaces -> PHONE Port -> PrimaryLine : SP1 Service
After a reboot, look to see if you have SIP registration:
Status -> SP1 Service Status -> Status : Registered (server=w.x.y.z:5060; expire in xxxs)