Specifications

Supported media modules in the G450
Issue 1 January 2008 21
Note:
Note: The MM720 BRI media module cannot be administered to support both BRI
trunks and BRI endpoints at the same time. Also, the MM720 BRI media module
does not support combining both B-channels together to form a 128-kbps
channel. Finally, if the MM720 BRI Media Module is administered to support BRI
endpoints, it cannot be used as a clock synchronization source.
For BRI trunking, the MM720 BRI media module supports up to eight BRI interfaces to the
central office at the ISDN TE reference point. Information is communicated in two ways:
● Over two 64-kbps channels, called B1 and B2, that can be circuit-switched simultaneously
● Over a 16-kbps channel, called the D-channel, that is used for signaling. The MM720
occupies one time slot for all eight D channels.
The circuit-switched connections have an A- or Mu-law option for voice operation. The
circuit-switched connections operate as 64-kbps clear channels when in the data mode.
For BRI endpoints, the MM720 BRI media module supports up to 16 BRI stations and data
modules that conform to AT&T BRI, World Class BRI, and National ISDN NI1/NI2 BRI
standards. The MM720 BRI media module provides -40 volt phantom power to the BRI
endpoints.
Figure 9: The MM720 media module
MM722 BRI media module
The MM722 BRI media module provides two 4 wire S/T ISDN BRI 2B+D access ports with
RJ-45 jacks. Each port interfaces to the central office at the ISDN T reference point. Information
is communicated in the same manner as for the MM720. See MM720 BRI media module
on
page 20.
Figure 10: The MM722 media module
Note:
Note: The MM722 media module does not support BRI stations or combining both B
channels together to form a 128-kbps channel.