From LQWiki

Like an email address it is an address used by the Session Initiation Protocol (SIP) to reach someone on the net.

It also has two parts separated by an @

1. the user name (ex : doe)
2. the provider name (ex: ekiga.net)

Thus John Doe address could be doe@ekiga.net

See also

• SIP
• VoIP News :What is a SIP address and where can I get one?