What is a SIP-URI?

A SIP-URI is the SIP addressing schema to call another person via SIP. In other words, a SIP URI is a user’s SIP phone number. The SIP URI resembles an e-mail address and is written in the following format:

SIP-URI = sip:x@y:Port  where x=Username and y=host (domain or IP)

Note: if you do not specify a port the default sip port will be assumed (5060). This is shown in the first two examples below.if you have changed the default sip port to something else then you need to specify it in the SIP-URI (third example)


  1. sip:joe.bloggs@
  2. sip:support@phonesystem.3cx.com
  3. sip:22444032@phonesystem.3cx.com:6000

The SIP URI standard has been defined in the RFC 3261 standard. 3CX Phone System for Windows uses SIP URIs.


RFC 2396 – Uniform Resource Identifiers (URI): Generic Syntax.