IP Phone

I need advice on buying a good IP phone which supports a USB port, so that I can communicate seamlessly with friends on all sides of this planet.

Where can I find a good comparison guide

I would prefer Linksys or Cisco, but i am open to other options

Kindly Advise me

at work I use an Avaya IP Phone but I know that Polycom phones are also ok

Are you using Asterisk for your back end?

nope, we use also use Avaya