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 interfaces must be SELV. If these interfaces are not SELV, you must use external line isolation units (LIU).
Auxiliary ringer jack: The Business Communications Manager uses the auxiliary ringer jack to control the cadence of an auxiliary ringer (customer supplied). You must use this output in a low current, low voltage application only. Do not use this output for switching the auxiliary ringer directly
This is a Signature and not part of the answer, it appears on every reply.
This is an Analogy so don't take it personally as some have.
Why change the engine if all you need is to change the spark plugs.