quite a bit, i can't be arsed to check the phone for precise call details but if those 'mobile phones fry your brain' things are true i'll be squishy jelly upstairs in no time.
Last summer I used it alot while traveling for work. I could go days without making or receiving a phone call. But I'm going to be traveling again so it will come in handy and I've already used it quite a few times in emergencies.
I use mine too much, so do the people I work with, if we are installing a network link, we usually have someone at either end, and - after the initial setup - will be on the a cell phone for as long as it takes to iron out any problems.