A Voice over Internet Protocol (VOIP) gateway is a network device that converts voice and fax calls between the public switched telephone network (PSTN) and an IP network in real time. A VOIP gateway is also known as a media gateway, networking equipment. With a minimum of one Ethernet and telephone port, the controlling of the gateway can be done through the application of various protocols: SIP, MGCP, LTP, etc.
The VOIP gateway basically operates voice and fax compression/decompression, packetization, control signaling and call routing. Other service features can include billing systems, network management systems, and interfaces to external controllers, like Gatekeepers or Softswitches.
Voice Over IP Gateway assists carrier services. It offer flexible call integration, ringing and sound (tones) quality, and supports the transference of the calls resulting in lower consumer costs combined with ease of access. Gateways also helps offer compliant, easy numbering plans, choosing the lowest cost route automatically while keeping transparency at both the ends.