In our last VoIP installment, we looked at the main reasons why SIP has become a widely adopted protocol, but we left details of the protocol’s inner workings fairly vague. This article will drill ...

The iptel.org 180+ page SIP tutorial is outstanding. Another overview that is a bit more market-oriented and nearly as long. White paper on the SIP value proposition over telephony, SIP and the new ...

SIP vs VoIP: what's the difference? If you’re setting up a new VoIP business phone system, this question will sound familiar. You've likely run into the acronyms SIP, or Session Initiation Protocol ...

In Part 1 of our SIP primer, I covered the SIP foundation layers starting from the message structure and ending with the SIP transactions. We saw how phone registrations and proxies could work using ...