What modules do you have?
It's a grounded system, so you need shielded wire to get it to work (Three terminals: Signal, Ground, Shield). And, it's 70V. Enough to knock a person off a ladder (I know from experience).The bogen equipment does not work, or at least I have yet to have success.
Most likely, they aren't. If they are, possible they can be unlocked.And, yes, the Asterisk cage is most likely useless.
The VoIP adaptors, it depends on if they are locked to a carrier or not.