Sentinel IP-SM-GW 3.0.0 :: Sentinel IP Short Message Gateway Architecture guide :: Registration Flows
Sentinel Express 2.8.0 :: Sentinel Administration Guide :: SIP Third Party Call Setup Feature
Third Party Registration in IMS: Notifying Application Servers of a User's Registration Status via SIP REGISTER Messages Sent by the S-CSCF | PDF | Ip Multimedia Subsystem | Session Initiation Protocol
How to register Third-Party SIP phones with Communications Manager - Cisco Community
Third Party SIP Endpoint Registration in CUCM | PDF | Session Initiation Protocol | Voice Over Ip