Gateway Control Protocols
This chapter covers two Internet Engineering Task Force (IETF) gateway control protocols that control Voice over IP (VoIP) gateways from external call-control elements: Media Gateway Control Protocol (MGCP) and H.248/MEGACO. These gateway control protocols are designed to support VoIP architecture, where the media functions are separated from call-signaling functions. Therefore, their use is prevalent in large trunking gateways and residential gateways. MGCP is widely deployed and is the focus of this chapter. H.248/MEGACO is another contending protocol, and it is briefly explained at the end of this chapter. MEGACO stands for media gateway control, but do not confuse it with MGCP.