Media Gateway Control Protocol (protocol)
The Media Gateway Control Protocol ( MGCP ) is a network protocol for controlling VoIP gateways . MGCP is described in RFC 2705 and is a master / slave protocol which transmits the control information in plain text (like SIP ). The VoIP gateway works as a slave and is controlled by a switching device (e.g. VoIP telephone system , in the standard English: call agent ).
functionality
MGCP gateways are controlled via eight different control information (commands). The control information is transmitted in plain text via UDP port 2427.
| Tax information | Surname | Channel | description |
|---|---|---|---|
| AUEP | AuditEndpoint | Call agent | Determines the status of a transferred connection (end point) |
| AUCX | AuditConnection | Call agent | Finds or reports all parameters of a connection. |
| CRCX | CreateConnection | Call agent | Establishes a connection between two end devices. |
| DLCX | DeleteConnection | Both | From the call agent: Terminates a current connection. From the gateway (interface): Indicates that a connection can no longer be held. |
| MDCX | ModifyConnection | Call agent | Changes the parameters of an established connection. |
| RQNT | NotificationRequest | Call agent | Instructs the gateway to respond to special events such as B. Pick up / hang up the phone or respond to DTMF tones . Is also used as an instruction to the gateway to transmit an audible tone to the end device (e.g. dial tone or busy tone). |
| NTFY | Notify | Gateway | Informs the call agent about requested events. |
| RSIP | RestartInProgress | Gateway | Informs the call agent that a device or a group of devices has been logged off or logged back on. |
Advantages and disadvantages
MGCP gateways are controlled by a central switching facility. The intelligence in the network is thus centralized. The implementation and administration of MGCP gateways is easier than H.323 gateways, since the central switching device takes over control. In contrast to H.323 gateways, the central switching facility always has the current status of the individual interfaces of a gateway.