- The remote user sends a SIP REGISTER request to the public IP address of the SBC.
- The SBC assigns a private IP address and port on the core side.
- The SBC establishes a binding between the remote users IP address and the associated IP address and port on the core side.
- The SBC replaces the contact address with the private IP address and port that it has assigned for the remote user.
- The SBC then delegates (i.e. passes on) the SIP REGISTER request to the Telephony Control Server.
The SBC uses a port mapping technique so that only one contact IP address is used for all the remote users but each user is assigned a unique port number at the single IP address.
When Lotus Sametime Unified Telephony wishes to route a call to a remote user, ...
- it sends a SIP INVITE to the topmost Via header address previously received in the SIP REGISTER request from the SBC, i.e. the SBC core-side interface
- it associates the Contact address in the SIP INVITE received at an IP address/port on the core-side with a specific remote users public IP address/port. For this step the SBC uses the registration binding information.
- it forwards the SIP INVITE from the access-side of the SBC to the remote user's device.
System Specific Information
When a phone is reset, a SIP REGISTER
with expiration time = 0 should be sent from the phone to remove the registration contact binding in the SBC and the Telephony Control Server. If the SBC detects a registration timer expiration for a user it must remove its registration contact binding and send a REGISTER
with expiration time = 0 to the Telephony Control Server.
Parent topic: Additional SBC (Session Border Controller) Capabilities