Don't Buy a Phone System
You deserve so much better.
Just say no. The game has changed. But not because of some new technology--the tech has been around for a while. What's different now is the affordability. It's the same with all technologies. Microwaves were around long before the TV dinner; GPS has only recently become reasonably priced.
Just as these innovations found their way into the consumer market, telecom technologies that used to be affordable only to large corporations are now transforming the way small- and medium-sized businesses communicate.
If you are looking for a new phone system (Why else would you be here?), please raise your expectations. You deserve so much better. You need a true IP solution, not the telecom giant or an "IP-enabled system." Just as you wouldn't top a gourmet sandwich with spray cheese, you shouldn't trust your company's communications with the standard phone system offering or inferior IP-enabled system. Both will leave a bad taste in your mouth.