SIP Registration Server

The registration server’s functionality typically stands in setting up and tearing down functionality with a client by using the registration and invite requests as well as clearing and retrieving registrations from a SIP url.

Let’s make some light about this register notion.

The Session Initiation Protocol provides a REGISTER functionality that is used mainly in a proxy configuration case. For what reason? The answer is quite simple. It’s about locating individual users in case of a call, which is similar to an INVITE message sent to the server.

The actual registration of a SIP user agent on a registration server is made using a pretty simple message flow like it follows.

• The user agent sends a REGISTER request to the server.
• The server sends back an acknowledgement message.

By changing some fields in the message the registration canceling is performed. Also interrogation of the server to identify contacts associated with a SIP url are made in the same way.