Thank you DrPbx, I am unclear as to what power supply is needed though. The PA is a Bogen TPU60B/PMC2000 combo. What needs a power supply?

I found a document at Mitel referencing a transformer to make a ring trip for the page port. Is that what you are refering to?

Here is the text from it:

If the PA Amplifier is one designed to work on telephone system analog station ports, then one of the telephone extension ports, (with the exception of the programming extension 20), can be programmed as the paging port and directly connected to the PA amplifier. On the amplifier, typically the input is marked "telephone" and has the internal 600 ohm transformer isolated input built in. It is recommended to check the amplifier's specifications. The Valcom V-997 is an example of this type..

If the paging amplifier is the type that provides a microphone input , a 1:1 Audio Isolation transformer with a 600-900 ohm impedance, must be connected between the extension port and the microphone input. A Radio Shack 1:1 Audio Isolation Transformer (p/n 273-1374 ) was used by Intertel to verify this operation, but any transformer with a similar specification will work. Also, commercial 1:1 (600 - 600 ohm) transformers are available from most sound system suppliers.