5. Supported Features

MGCP provides a rich but focused set of features for controlling media gateway functions. These features revolve around managing endpoint states, connections (media channels), signaling events (e.g., dial tones, ringing), and negotiating session parameters like codecs. The protocol’s base specification defines a core set of capabilities, and additional functionality is added via packages (extensions for specific endpoint types or services). Below, we detail MGCP’s supported features in key areas.

5.1 Endpoint Management (Ephemeral and Permanent Endpoints)

Endpoints in MGCP represent sources or sinks of media on a gateway. Managing endpoints is fundamental to MGCP. There are two broad categories of endpoints:
Permanent Endpoints (Physical Terminations): These correspond to fixed, pre-provisioned physical interfaces on the gateway – for example, a trunk circuit DS0 channel or an analog line port. Permanent endpoints exist independently of any one call; they are configured in the gateway (and known to the Call Agent by provisioning). In MGCP (and similarly in H.248), a physical termination is defined as an entity with fixed characteristics (e.g., an analog line with a specific circuit assignment) that must be pre-configured in the MGW and known to the controller [TS 183.025]. The Call Agent can directly address such endpoints by name (for instance, ds1/1@gateway1 might refer to the first channel of a DS1 trunk on a gateway). Permanent endpoints typically represent telephone lines, trunk channels, or other always-on ports. The MGCP Call Agent can audit them, seize/release them via connection commands, or request events on them.