Signalling and MGW Channels
Forum Gateway 560
77
Signalling and MGW Channels
Each Forum Gateway 560 requires at least one Media gateway interface card
Forum 550 Media Gateway Card (see also
starting on page 130). This interface card provides 16 VoIP audio channels
which are realised as RTP data stream with the G.711 (A-Law) or G.729
codecs. The following applies generally: Each audio connection which leaves
the Forum Gateway 560 via a VoIP connection requires a MGW channel.
TDM and VoIP Forum Gateway 560 connections
A MGW channel is seized when an audio connection between VoIP and TDM is
to be established. Alongside call connections from VoIP telephones to TDM
terminals or TDM lines, this comprises:
●
call connections between 2 TDM terminals connected to different
Forum Gateways 560. Exception: Both Forum Gateways 560 are
connected via PCM-V line.
●
Music on Hold: generated as VoIP data stream by the Forum 5004/5008/
5012 communications system.
●
Forum Voicemail and Forum Auto Attendant: Recording and playing as
VoIP data stream via the Forum 5004/5008/5012 communications
system.
●
Audio tones such as ringing tone, busy signal, dialling tone, etc. are
generated as VoIP data stream by the Forum 5004/5008/5012 commu-
nications system.
Seizure of MGW channels is (inasmuch as possible) optimised by the
Forum 5004/5008/5012 communications system. Example: A call
connection between an external TDM line and a TDM terminal on the same
Forum Gateway 560 does not seize a MGW channel. This is additionally
supported by a line selection which prioritises according to terminal type
Gateway
Gateway
VoIP
TDM
TDM