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-URIs are defined in RFC-3261.

Why Should Anyone Care?

There's a quiet revolution underway as the old 4 kHz narrowband phone system is being disrupted by a combination of cell phones and Internet phones with better features and wideband audio (HD). Any phone call that passes through the PSTN (Public Switched Telephone Network) is reduced to narrowband audio and incurs a toll. As a result, there is growing interest in dialing SIP calls directly from one SIP Internet phone to another, bypassing the PSTN completely. SIP-URIs provide an industry standard way of doing this. If you have your own registered domain name, your Email address can be your SIP-URI.

Dialing SIP-URIs

The telephone keypad on most phones is not optimized for entering SIP-URIs, so this is an ideal application for Phone Amego. Phone Amego allows SIP-URIs to be entered anywhere a phone number is normally used, and will pass the SIP-URI unmodified to the telephone device or service selected. A growing number of IP phones (i.e. Polycom and Yealink) and VoIP services (ie CallCentric) can handle these correctly. You can try it yourself by dialing sip:wbdemo@conf.zipdx.com in Phone Amego.

Phone Amego also handles URLs of the form allowing you to click on these links wherever they appear.

Where to Store SIP-URIs

Since SIP-URIs are similar to Email addresses, they cannot be stored properly in the phone number field of a person record in your Address Book. Apple's Address Book has a URL field type which is perfect for holding a SIP-URI. What I've done is create a custom field in my Address Book of type URL with the label "sip" to hold SIP-URIs. Clicking to open this URL will place the corresponding call with Phone Amego.

Over time I'll be adding more integrated support for SIP-URI handling between Apple's Address Book and Phone Amego. Searching for a matching contact in your Address Book should include any SIP-URIs.

Selecting Default Applications

Phone Amego registers to handle URLs of the form , but other applications may register for these as well in which case Launch Services will decide which application to invoke.

You can select which application you want to launch by default for various URLs by installing a 3rd party preference pane called "Default Apps".  See

Q: What's a URI?
A: URI stands for Uniform Resource Identifier. It is similar to a URL (Uniform Resource Locator) but identifies a network resource like a phone rather than the location of a mailbox or document.

Q: How do I assign a SIP-URI to my IP phone?
A: You need to use a service that provides SIP name registration. VoIP service provider CallCentric does this, and has peering agreements to allow free SIP-URI calls to most major providers. Other providers like OnSip can also provide SIP-URI registration. If you have your own registered domain name, your Email address can be your SIP-URI.

Q: Can I call Google Voice using a SIP-URI?
A: Maybe. Many users report this works if your VoIP provider has a peering agreement with Google. The format of the SIP-URI is:
This works for me using CallCentric.

Q: Can Google Voice forward my calls to a SIP-URI?
A: Not directly at this time.