What phone systems do you use for your business?
datums: Take a look at trixbox (asterisk) http://www.trixbox.org/downloads , it's easy to install has all the basic functionality you need. You can also setup the IVR to route calls to specific people. I replaced a windows t1 voice system with this for 25 people, 8 were remotely connecting to it over SIP. If you don't feel like managing your own setup go with a hosted service.