SIP Address Of Record


SIP defines user identity by unique AOR. SIP's AOR (address of record) is formed by combining the name of SIP phone user (Alice) with the name of the SIP server ( using the "@" sign as in this example:

In the above picture, Alice and Bob are SIP phone users.  Alice registers her phone with Atlanta SIP server.  The Atlanta SIP server creates a database entry for Alice to keep her SIP phone's IP address and her AOR,

Bob registers his SIP phone with Biloxi SIP server.  The Biloxi SIP server creates a database entry for recording Bob's IP address and his AOR,

Note:  The names: Alice, Bob, Atlanta, Biloxi and others are used throughout the SIP RFCs.  The same names are reused here.

Alice calls Bob using his URI.  Alice enters the following URI when she calls Bob (very much like entering the ten-digit phone number in a PSTN call).  The SIP URI (Uniform Resource Identifier) is formed by prefixing the AOR with "sip:" as shown here:

When Biloxi server receives the call request, it extracts Bob's AOR from the URI and uses it to look up the database for the IP address of the registered phone.  The server uses the IP address to send the call request to Bob's phone.

SIP AOR is easier to remember than a phone number that was assigned by a phone carrier because of two reasons:
  • The users create their own AORs, not the carriers
  • AORs can be made of easy to remember names.  Assigned random 10-digit phone numbers are harder to remember.
For more information on creating your own AOR / URI, see SIPsocial URI.

Read more on phone number.