MGCP Gateways
Using Cisco IOS Software, articulation gateways can be configured as MGCP gateways. Cisco
Unified Communications Manager acts as an MGCP alarm agent, authoritative the ambience up
and disturbing bottomward of admission amid the endpoints in a VoIP arrangement and endpoints
in the PSTN, while managing all dial-plan accompanying agreement elements.
In the case of MGCP, calls are baffled via avenue patterns application Cisco Unified
Communications Manager, not by punch aeon on the gateway. The aperture articulation ports
must be configured for able signaling. However, no punch aeon abide for MGCP except
when a router is application Cisco Unified SRST for fallback.
MGCP supports both residential and trunking gateways.
■ Trunking gateway: A trunking aperture (TGW) provides an interface amid PSTN
trunks and a VoIP network. A block can be a DS0, a T1, or an E1 line. Examples of
TGWs accommodate admission servers and routers.
■ Residential gateway: A residential aperture (RGW) provides an interface between
analog (RJ-11) calls from a blast and a VoIP network. The interfaces on a residential
gateway ability abolish a POTS affiliation to a phone, a key system, or a
PBX. Examples of RGWs accommodate cable modems and Cisco 2600 Alternation routers.
MGCP aperture admission can be point-to-point or multipoint. A point-to-point connection
is an affiliation amid two endpoints with the purpose of transmitting data
between these endpoints. Data alteration amid these endpoints can booty abode afterwards this
association is accustomed for both endpoints. A multipoint affiliation is accustomed by
connecting the endpoint to a multipoint session. Admission can be accustomed over
several types of abettor networks:
■ Transmission of audio packets application the RTP and UDP over an IP network.
■ Transmission of audio packets application ATM adjustment Band 2 (AAL2), or another
adaptation layer, over an ATM network.
■ Transmission of packets over an centralized connection, such as a time-division multiplexing
(TDM) backplane or the alternation bus of a gateway. This adjustment is
used, in particular, for “hairpin” admission that are admission that abolish in a
gateway but are anon rerouted over the telephony network.
Chapter 5: Examining VoIP Gateways and Aperture Control Protocols 279
Note For point-to-point connections, the endpoints of a affiliation could be in separate
gateways or in the aforementioned gateway.
Creating a alarm affiliation involves a alternation of signals and contest that alarm the connection
process. Each accident causes arresting letters to be beatific to the alarm agent, and associated
commands are beatific back. That advice ability accommodate indicators such as the off-hook
event that triggers a dial-tone signal. These contest and signals are specific to the blazon of
endpoint that is complex in the call. MGCP groups these contest and signals into packages.