Well, it will work with any phone - but you might need to buy more things.

If you have a desk phone that has a headset jack, you can buy the appropriate cord from Plantronics to connect the headset base with the phone. Some phones (like the Cisco 7960 IP Phones my company uses) can go off hook without lifting the handset. If you don't have such a phone, you can buy a handset lifter that will manually raise the handset and take the phone off hook when you press the button on your headset.

I'd suggest getting the W740 because it comes with the FitKit that lets you wear the headset with a headband, a behind-the-head headband, or the ear clip. I like the ear clip. The FitKit also comes with multiple ear pieces (the little soft piece that goes in/on your ear). They cost about the same.