High Quality Content by WIKIPEDIA articles! A Media Gateway Controller (MGC) is a system used in certain Voice over IP telephony architectures. An MGC controls a number of dumb terminals, the Media Gateways. The MGC receives signalling information (like dialed digits) from the Media Gateway and can instruct it to alert the called party, to send and receive voice data etc. There are several protocols which can be used between MGC and Media Gateway: SGCP, IPDC, MGCP and Megaco (also known as H.248). The MGC receives also the term Call Agent when referred in the context of MGCP.