...learn how to save costs by choosing the right IP office phone system. Many companies are transitioning from either a Centrexservice or Key system / PBX product to a state-of-the-art Hosted IP or IP PBX telephony solution for immediate cost...
http://www.sys-con.com/node/1185829
...spending on voice and data services Sprint IP Voice Connect Your current phone system, whether it is a key system, Centrexservice or a private branch exchange (PBX), manages your incoming and outgoing calls, provides a set of calling features...
http://www.findwhitepapers.com/whitepaper3330/