Let’s start with the gateway. This unit allows a call to be made from the Internet to a standard telephone. Gateways can either be analog or digital. Analog gateways have analog telephony interfaces like RJ11. On the other hand, digital gateways of course have digital interfaces like T1/E1/PRI.
VoIP gateway performs different task depending on where it is used, either at home or at the office. In the office, the gateway refers to the computer that routes the traffic from a workstation to the external network that caters to the Web pages. The gateway node also usually acts as a proxy server as well as a firewall. Meanwhile at homes, the gateway is the Internet service provider or the ISP that connects the user to the Internet.
The gateway is also linked with both a router that utilizes headers in order to forward tables to verify where the packets are sent, and to a switch that provides the actual path for the packet that goes in and out of the gateway. By the way “headers” are actually part of the data packet and this holds transparent information regarding the file or the transmission.