How is this possible?

[BeauJangles]

I was calling a good friend of mine last night. I've called her plenty of times before by finding her name in my cell's contacts and pressing send. Last night, however, my cell showed it was dialing her number but I got some random woman who had no idea who I was asking for and, I might add, was a bit hostile.

Has this ever happened to you?

Does anyone know HOW it happens?