Gateway Control Protocols (GCPs) supports a centralized VOIP Network. The key components are: Media Gateway Controller(MGC), Media Gateway(MG); Signaling Gateway (SG) and Endpoints. There are too many scenarios of call flows under the Gateway Control Protocols (GCPs).

Call between two residential gateways
Case (a).calling party call termination
Case (b).called party call termination
Case (c).called party busy
Call between Residential Gateway and Trunking Gateway
Call between Trunking gateway and Residential Gateway
Call between two Trunking gateways
Call between Residential gateway and SS7 trunk in TGW
Call between SS7 trunk in TGW and residential gateway
Call between SS7 trunk in TGW and R2 trunk in TGW
Call between R2 trunk in TGW and SS7 trunk in TGW
Call between R1 trunk in TGW and SS7 trunk in TGW
Call between SS7 trunk in TGW and R1 trunk in TGW
Call between ISDN trunk in TGW and SS7 trunk in TGW
Continuity test from TGW
Call from residential gateway to H.323 Terminal
Call from residential gateway to SIP user

We are not going to provide the details of the call flow steps in this article. The original IETF RFCs provide all the details.

Example Call Flow based on MGCP

Related Terms: MGCP call flow, GCP call flow, Megaco call flow, H.248 call flow

Reference Links: http://www.javvin.com/protocolVOIP.html: VOIP Protocols