What is the purpose of SIP registration?

The purpose of SIP registration is to allow a user to associate their identifier (such as a SIP URI) with their current location, which is typically their IP address. When a user registers with a SIP server, they essentially inform the server about their current location, enabling the server to route calls to them correctly when someone tries to reach their SIP identifier. This registration process ensures that the system can direct incoming communications to the right endpoint, even if the user changes IP addresses or networks. This functionality plays a critical role in the SIP architecture, as it enables users to maintain connectivity regardless of their location.

Other options do not align with the primary purpose of SIP registration. For instance, terminating inactive calls relates more to session management rather than the registration process itself. Establishing a direct media path involves media handling, which occurs after call setup through signaling and is not related to the registration function. Converting telephone numbers into SIP accounts pertains to the process of mapping traditional telephony to SIP infrastructure, rather than the specific role of registration in user identification and location association.