Help me find a software!

What communications software does your company use? I've been tasked to do some research by our company of possible candidates for the overhaul that they are planning? We need something that can manage phone calls, faxes, e-mails and more. Preferably something that runs on Windows. Our company wasn't satisfied with the one we were using before.
Any advice or suggestions?

We have a secretary to do all those things, actually I haven't heard of that kind of software. So how does is manage phone calls I'm curious.