Has anyone come across a away to get the B179 conference phone to register and work as an ordinary SIP phone not on IP office?

Yes, we've done it - there shouldn't be an issue. Are you getting stuck somewhere in particular?

I can get it to register, I can call it, but when trying to call out from it either internal or external numbers it says "denied"

Can you get any SIP trace from the service or PBX you have it registered to? It sounds like the outgoing number may be formatted incorrectly (missing leading + or 1) or perhaps the authentication is not working.

That's the funny part. It is to a premise system.

Well, I would suggest doing a packet capture of the SIP messages using Wireshark. If you can do that and post the INVITE message followed by the PBX response, we can probably point you in the right direction!