Voip

Experimenting with SIP and call timing on a gateway

One of the fundamental functions of many home and business gateways is to act as a SIP ALG (Application Layer Gateway) for setting up, routing, and terminating VoIP telephone calls. This presents some difficulty with Network Address Translation (NAT) functionality that we’ve covered before. However, there’s other functional behavior when it comes to SIP call setup and the resulting RTP streams that can be missed without some rigorous experimentation. Read more...