What Is a SIP Address?

SIP opens the door to Voice-over-IP voice and video calls

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Session Initiation Protocol facilitates calls over the internet and other IP networks. Just like a phone number, a SIP address is a unique identifier for each user on the global phone network or for an email address. It is also known as a SIP Uniform Resource Identifier.

You receive a SIP address when you register for a SIP account, and it acts as a communication handle that people use to contact you. SIP addresses can be translated into phone numbers, which can be easier to track as contact identifiers than SIP addresses.

Savings achievable with a SIP account are in the range of 40 percent for domestic calls and 90 percent for international calls.

Why Get a SIP Account?

Use a SIP account to set up VoIP desk phones, soft phones, and mobile VoIP clients. A SIP account opens the door to free video calling and HD voice calling on many platforms including Windows and Mac computers and iOS and Android mobile devices. SIP-to-SIP calls made between any two SIP addresses over the internet are almost always free.

For companies that have many international contacts, SIP offers huge savings. Because it is a VoIP service with few hardware purchases and low maintenance costs, it quickly pays for its installation and adoption by workforces.

Although this may all sound confusing, SIP calling is user-friendly after only a brief training session. In most cases, the sound quality is better than with a wired phone service.

Small businesses and startups use SIP accounts to avoid the initial hardware purchases and installations required by wired phone lines.

Structure of a SIP Address

A SIP address resembles an email address. The structure is:

sip:user@domain:port

As an example, this is a SIP address obtained by registering with Ekiga:

sip:nadeem.u@ekiga.net

In this example, sip denotes the protocol and does not change. It starts every SIP address. Some SIP addresses are passed without the sip part since it is understood as the format.

The user name is the part you choose when you register for a SIP address. It can be a string of numbers or letters. In this example, the user part is nadeem.u. In other addresses, it may be a phone number (as used for SIP trunking for PBX systems) or any other combination of letters and numbers.

The At symbol (@) is mandatory between the user and the domain, as is the case with an email address.

The domain name of the service you registered with appears immediately following the At symbol. It can be a fully qualified domain or simply an IP address. In this example, the domain is ekiga.net. Other examples are sip.mydomain.com and 14.18.10.23. You don’t control the domain name as a user.

The port is optional and is absent from SIP addresses most of the time because there is no technical reason for their explicit presence in many cases. When a port appears, it denotes the port to access on a proxy server or another server dedicated to the SIP activity.

Examples of SIP addresses include:

  • sip:500@ekiga.net, the Ekiga test number used to test a SIP configuration
  • sip:8508355@vp.mdbserv.sg
  • sip:12345@14.18.10.23:5090

A SIP address is different from a phone number and an email address in that it is attached to the user and not to the service provider. It follows you wherever you go and is not tied to the service as is a phone number.

Where to Get a SIP Address

You can obtain free SIP addresses from several providers online.

How to Use a SIP Address

Use your SIP address to configure a SIP client. Businesses use a service to set up the system and provide a SIP address for each employee. Then give the SIP address to your friends and clients who use SIP so there is free voice and video communication between you and them.

You can also use your SIP address to contact people who don’t use SIP on their landline or mobile phones, this requires a paid service to terminate the call from the IP network to the phone network.

Don't overlook the VoIP services out there. People who use regular phones can also call you on your SIP address, but you need to have a phone number attached to the SIP address, which is their handle to you.

For communication over the internet, SIP is interesting, with the many features associated with voice and video calls, often involving multiple parties. For that, choose a good SIP client and enjoy.