MiVoice 250 bogen talkback module problem

[Tripoth]

Have a MiVoice 250. Mitel support says it is very similar to the 5000 platform.
Have installed a Bogen PCM 2000 system with a talkback module.
Testing the PCM midule without the system the talkback works.
Paging through the phone system, the paging works, but no talkback.
Have the paging zone set up with with a loopstart trunk port. I have been told the paging zone only allows one way communication, so the talkback will not work.
I am wondering if there is a workaround anyone knows of to get the talkback working on the system?
Maybe installing a UPAM module?
Using a station port?

Thanks for any assistance you can give.