SIP URI (SIP Address)
A SIP URI is the address of a SIP user or service, in the form sip:user@domain, optionally with a port and parameters. Learn how it is built and used.
Published 8 November 2026 · 1 min read · By SpaGreen Creative
Short answer
A SIP URI is the address of a user or service in SIP, written as sip:user@host with optional port and parameters, or sips: when secure transport is required.
A SIP URI identifies who or what a SIP message is addressed to. The basic form is sip:user@host, for example sip:201@pbx.example.com. The user part is often an extension number or account name. The host part is a domain name or IP address, and it may include a port such as :5060. Parameters can follow a semicolon, for instance ;transport=tls.
RFC 3261 section 19.1 defines the syntax. The sips: scheme, clarified in RFC 5630, indicates that the request should travel over a secure transport on every hop.
SIP URIs appear in several places. The Request-URI at the top of an INVITE names the destination. The From and To headers identify the parties. The Contact header carries the URI at which the sender can be reached directly, which is what a registrar stores during registration.
In a softphone you usually do not type full URIs. The app assembles them from the Server, Domain and Username fields, and when you dial a number it builds sip:number@domain for you. The SIP URI generator tool on this site shows the result for a given set of inputs.
Sources and further reading
- RFC 3261: SIP: Session Initiation Protocol, Section 19.1 SIP and SIPS URIswww.rfc-editor.org
- RFC 5630: The Use of the SIPS URI Scheme in SIPwww.rfc-editor.org
This article is published by SpaGreen Creative, the maker of SIPdia. Product names mentioned belong to their owners. Where it describes other software, treat the steps as general guidance and check the official documentation linked above.
