MGCP separates the functions of call control and media translation into
two separate devices:
- The voice gateway handles
- A call agent handles
This following text gives a brief overview of how MGCP functions and
how you implement these functions using Cisco Unified Communications Manager as
the call agent.
An MGCP gateway routes calls in response to instructions from the Cisco
Unified Communications Manager. These calls can be to or from a telephone on
the PSTN, or across a WAN to an IP or analog phone at a remote site. The
gateway does not make call routing decisions. It needs to be able to reach a
Cisco Unified Communications Manager before it can handle calls. When you are
using an MGCP gateway, all the dial plan knowledge resides on the Cisco Unified
Communications Manager. You do not need to configure dial peers, unlike H.323
and SIP. However, this leaves the gateway unable to route calls if it cannot
reach a Cisco Unified Communications Manager.
Cisco Unified Communications Manager supports only version 0.1, but
Cisco gateways can use version 1.0 with other call agents.
Cisco Unified Communications Manager is able to exercise per-port
control of connections to the public switched telephone network (PSTN), legacy
private branch exchanges (PBX), voice-mail systems, and plain old telephone
service (POTS) phones. This allows complete control of the dial plan from Cisco
Unified Communications Manager, which centralizes gateway management and
provides scalable IP Telephony deployments.
One gateway can support multiple endpoints. Endpoint names have two
components, a local identifier, and a gateway identifier. The entire name
consists of the local identifier, followed by the @ symbol, and then the
gateway identifier. For example:
The gateway identifier is its configured hostname, such as
MGCP-router. If the gateway is configured with a domain
name, it is appended to the end of the hostname, such as
The format of a local identifier varies depending on the type of
interface. The local identifier for analog ports uses the following syntax:
Endpoint type/Slot #/Subunit #/Port #
MGCP was created for a centralized architecture, where most of the
configuration and call-control intelligence resides on a call agent, such as
Cisco Unified Communications Manager. The traditional role of an MGCP gateway
is media translation. PSTN connections, such as Foreign Exchange Office (FXO),
Foreign Exchange Station (FXS), and PRI lines, typically terminate in the
gateway. The gateway then translates between the PSTN and the IP network.