Does anybody's phone randomly turn off? And if so, what kind of phone do you have?

I used to have the verizon juke and this happened all the time. It was a swivel phone. I was young so I didn't bring it up to get it fixed because I didn't realize I could. Now I have a verizon ally which is an android phone with a slide out keyboard and I still have this problem, just not as much. Verizon says its a problem with the network and that it doesn't happen often. My sister has a droid from verizon also and has so many issues with her phone but verizon insists that these problems don't exist. Or they send a replacement phone that has more problems than the original phone. When my contracts up I am so switching to virgin mobile, I hear good things about them.