58 Chapter 2 Introducing the BCM50 hardwareNN40020-302RJ-21 telephony connectorUse the RJ-21 telephony connector to connect a 25-pair (RJ-21) cable to the main unit. Then usethese 25 pairs of wires to connect to the following telephony devices (see RJ-21 telephonyconnector wiring chart on page 207):• Four analog lines (standard main units only)Use these connections for analog trunks from the Public Switched Telephone Network(PSTN). The four analog lines on the RJ-21 telephony connector are not available on the BRIseries (b-series) main units.• Four analog telephonesUse these connections for analog telephony devices such as single-line telephones, faxmachines, and modems.• Auxiliary ringerUse this connection for an auxiliary ringer (customer supplied). The BCM50 system uses theauxiliary ringer to control the cadence of an auxiliary ringer. You must use this output in alow-current, low-voltage application only. Do not use this output for switching the auxiliaryringer directly.• Page outputUse this connection to connect an internally generated voice-paging signal to an externalpaging amplifier (customer supplied).• Page relayWhen you use the page output to connect an external paging amplifier, you also use the pagerelay. The page relay connects to a floating relay contact pair. The BCM50 system uses thepage relay to control the external paging amplifier.• Music inputUse the Music 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 anyavailable radio or music source approved for connection to the network. If you use thisconnection, do not use the Music input jack on the main unit faceplate.• Twelve digital telephonesUse these connections for digital telephones. For a list of digital telephones that are compatiblewith the BCM50 system, see the Telephony Device Installation Guide (NN40020-309).Warning: External equipment connected to the auxiliary ringer, page relay, page output,and music-on-hold interfaces must use safety extra low voltage (SELV).All four interfaces are SELV and the external equipment connected to these interfacesmust be SELV. If these interfaces are not SELV, you must use external line isolation units(LIU).Note: The analog trunk interfaces and analog telephony device interfaces on the RJ-21telephony connector are compatible with the North American telephony interfacestandards only.If your BCM50 system is in a country that uses a different telephony standard, you mustuse media bay modules for your analog trunks and media bay modules or ATAs for youranalog telephony devices.
