This Recommendation describes a profile of an application programming interface, Media Gateway Controller Interface (MGCI), and a corresponding protocol, Media Gateway Control Protocol (MGCP), for controlling voice-over-IP (VoIP) embedded clients from external call control elements. The MGCP assumes a call control architecture where the call control "intelligence" is outside the gateways and is handled by external call control elements. The profile, as described in this Recommendation, will be referred to as the Network-based Call Signalling (NCS) Protocol.