Thanks guys,
As you may have guessed, I'm come into this sideways and am just sorting things out.
I should have given the backstory to my question.
Our regional office had been running Cisco Call manager with Cisco
7960's for years. Then our head office brought in the NEC NEAX 2000 IPS pbx with the digital handsets (dterm) and mothballed the cisco equipment. The goal was to have us all on the same equipment and allow queueing, 4 digit dialing, etc between both offices. The IP connectivity is between the two offices.
The system is working well with the exception of how much work is involved in maintaining staff moves and changes-- lots of rewiring and manual maintaining of the handset port list.
This all happened before my time with the company.
Seeing as how we have the Cisco equipment already, I thought it would be worth figuring out if we could get at least the phones to co-exist. The re-wiring of extensions is fairly time consuming with the dterm digital phones and it would be a huge win to not have to do that anymore.
Thanks for your suggestions and patience-- At least I know this is possible :-) . Also thanks for the pointer to the network diagram.