2.- SIP Addressing

In SIP (Session Initiation Protocol), addressing is used to identify the endpoints of a SIP session. SIP addressing is based on the use of SIP Uniform Resource Identifiers (URIs), which are used to identify the SIP endpoints.

A SIP URI is a string of characters that identifies a SIP endpoint, similar to a URL that identifies a web page. A SIP URI has the following format:

The sip: prefix indicates that this is a SIP URI. The user part of the URI identifies the user or device within the domain, and the domain.com part of the URI identifies the domain name of the endpoint.

In addition to the user and domain parts of the URI, SIP URIs can also contain other parameters, such as port numbers and transport protocols. For example, a SIP URI for an endpoint using the secure transport protocol over port 5061 would look like this:

SIP addressing can also include other elements such as the SIP message header fields, which provide additional information about the session, including the address of the sender and receiver, the type of session being initiated, and other session-specific information.

The SIP addressing scheme is flexible, allowing for the identification of a wide variety of SIP endpoints, including phones, softphones, SIP servers, and other SIP-capable devices.