Nortel BCM 3.5 Handbook - Digitcom

The MSC has four 3.5 mm (1/8 inch) miniature jacks located on the faceplate. These jacks
are standard miniature stereo (three-conductor) jacks. All four interfaces are safety extra low
voltage (SELV) and the external equipment connected to these interfaces must be SELV. If
these interfaces are not SELV, external line isolation units (LIU) must be used.
Figure 2-5
The miniature jacks are used to connect the following optional equipment:
• Music on Hold input
The BCM uses the Music on Hold input to connect an external music source that supplies a
signal to held lines (Music on Hold) or telephone speakers (background music). The input
source can be any customer-supplied radio or music source, provided that it is approved for
connection to the network.
The music source connects to the tip and sleeve terminals of the miniature jack. The sleeve
terminal of the jack connects to ground. A mono or stereo plug can be used to connect the
music source. However, the Music on Hold input only accepts a mono input.
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