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 ...

To "prove" that ALG is off, target a host on a public IP with your SIP client, and run a packet capture there. In the "Contact: <sip:[email protected]>;expires=3600" line of the registration ...

Last time I gave a high level overview of SIP and also took a look at SIP network element types. This time, I’ll be looking at SIP message and method types, and describing how SIP network elements ...

Testers recently found a vulnerability in the Session Initiation Protocol (SIP), an emerging standard used for connections between devices in IP networks such as voice-over-IP phones (see story). But ...

For all the technology behind Voice over IP (VoIP), you'd expect that it would work on every network, but this unfortunately isn't the case. Network Address Translation (NAT) is a common practice used ...

H.323, the ITU's umbrella standard for audio, video and data-sharing over packet (IP) networks, is already widely deployed and has significant market share. SIP, the IETF's multimedia signaling ...