Subscribe to the Nextiva blog newsletter for the latest content on Customer Service, Productivity, Marketing and VoIP.

What Types Of Servers Does SIP Use?

There are five main types of SIP servers: the registrar server, the location server, the redirect server, the proxy server, and the presence server. The registrar server allows online users to be available for calls, to both initiate and receive calls. The registrar registers and authenticates users. The registrar server also records the user information, which is identified by URIs. The location server tracks users locations and provides key information for the proxy and redirect servers. This allows for the correct initiation and maintenance of sessions from logical SIP addresses to physical SIP addresses.The redirect servers connect users who are outside their home domains by redirecting sessions. The redirect server takes SIP requests and forwards it to the device closest to the user. For example, if a call is sent to a user’s email, but the user is not available at the email, then the call can be forwarded to the user’s cell phone. A proxy server only acts in the initiation and the termination of sessions by transferring SIP requests down the line of servers and devices, while sending responses upstream about the progress. Once a connection is established with use of the proxy, communication continues directly between users. Presence servers store information of available contacts; the server is made up of presentities, who provide information, and the watchers, who receive the information.

About the author

Yaniv Masjedi serves as Nextiva's CMO. An avid reader and lover of all things marketing, leadership, and personal growth, Yaniv is obsessed with creating strategies that drive awareness, strengthen brands, and create customer-centric culture. To get in touch, follow Yaniv on LinkedIn.