My 2-cents worth!! I would go with a Norstar. You will get the most longevity with this system. The new T7316E sets will give you enough keys to have line apperances on all the sets. You can add key indicator modules to the 7316 sets with 24 keys to each module, up to a maximum of 9 modules per station. The new Call Pilot voice mail will not only give you good service, but if you use the desktop messaging, you can foward voice mail from your e-mail client to anywhere via a WAV. file. Another feature likable by attourneys, is the call record feature. You will by far get better service from the Norstar than any other system on the market. Am I biased, Yes, but I have also been in this business for 30 some odd years, and when something works, I tend to stick with it. Just go to
www.nortelnetworks.com/norstar and look up a channel partner in your area.
Oh, as for the T-1 line. You can use this and still have line apperances on your sets. It will give you alot less headaches than regular copper (or analog lines). Also, ditch the centrex, you have no need of this service!!!