Voice over IP Basics (2): Gateway's
January 11, 2001
As we all know the Internet spans the whole world and you can find a place to connect to the Internet at the most strange places in the world (i.e. easyinternet from EasyEverything). Today many websites are sound enabled. Voice over IP uses the IP protocol to send audio between one or more computers in real time, so that users can converse. When Vocaltec introduced their first IP telephony software in 1995, they caught the world's attention. VoIP has become one of the hottest items at the moment, but VoIP wouldn't be that hot if there was no connection between the Internet and the traditional PSTN networks. If there where no connection you have two separate networks and that is not what we were waiting for. To make a connection between the two networks you use a gateway.
What does a gateway:
By bridging the traditional circuit-switched telephony world to IP related
networks, gateways offer the advantages of VoIP to the most common, cheapest,
most mobile, and easiest-to-use terminal in the world : the standard telephone.
How does it work:
Picture 1 represents a simple layout of a gateway.
Picture 1: Simple Gateway scheme
On the Phone to network connection the gateway connects to the PSTN. You can
connect any phone you like at this side. At the other side the gateway connects
to an IP network, this side can communicate with every well equipped PC or IP
phone in the big world of communication.
Two very important functions of an gateway are:
In the article above I described the most basic features of the gateway and what they mean in the VoIP world.