Looking into VoIP System

Hello,

Currently all the phones in my network are Cisco 7940. We get our
phone service through our ISP who outsources it to a company about 5
hours from here. My company asked me to look into purchasing the
entire back end of the system so that we can administer everything
ourselves. I realize that this means purchasing alot of equipment.
Can someone give me a place to start looking, or a su ..
Telecom, Cabling and VoIP continues...
Tags: Broadband