SIP is used to make calls over the Internet and other IP networks. A SIP address is a unique identifier for each user on the network, just like a phone number identifies each user on the global phone network, or an email address. It is also known as a SIP URI (Uniform Resource Identifier).
A SIP address is what you get when you register for a SIP account, and it acts as a communication handle that people use to contact you. Often, through ENUM, SIP addresses are translated into phone numbers. This way, you can have a SIP account whose SIP address is translated into a phone number; phone numbers are more acceptable to common people as contact number than a SIP address.
Structure of a SIP Address
A SIP address resembles an email address. The structure is like this:
As example, let’s take the SIP address I just obtained after registering with Ekiga:
“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 that this part automatically takes its place.
“user” is the part that you choose when you register for a SIP address. It can be a string of numbers or letters. In my address, the user part is nadeem.u, and in other addresses it can be a phone number (as used for SIP trunking for PBX systems) or any other combination of letters and numbers.
The @ sign is mandatory here between the user and the domain, as is the case with an email address.
“domain” is the domain name of the service you are registering with. It can be a fully qualified domain or simple an IP address. In my example, the domain is ekiga.net. Other examples are sip.mydomain.com, or 18.104.22.168. You don’t choose that as a user, you just get it with the service.
“port” is optional, and is most of the time absent from SIP addresses, maybe because they freak users out, but surely because there is no technical reason for their explicit presence in many cases. It denotes the port to access on a proxy server or any other server dedicated to the SIP activity.
Here are some more examples of SIP addresses:
sip:firstname.lastname@example.org, the Ekiga test number which you can use to test your SIP configuration.
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. That is, it follows you wherever you go and not the service as does a phone number.
Where To Get a SIP Address
How To Use My SIP Address
Firstly use it to configure a SIP client. Then give it to your friends who use SIP so that there can be free voice and video communication between you and them. You can use your SIP address to contact people who don’t use SIP, on their landline or mobile phones. You then need a paid service that will terminate the call from the IP network to the phone network. Consider the VoIP services out there. These people (using regular phones) can also call you on your SIP address, but you will need to have a phone number attached to the SIP address, which will be their handle to you.
For communication over the Internet, SIP is quite interesting, with the many features associated with voice and video calls, often involving multiple parties. For that, choose a good SIP client and enjoy.