I've only changed mine once. I don't remember why, maybe I was switching carriers and taking my sister's friend's place in the plan or something, but I once had the opportunity to change my number to my sister's friend's number. I opted yes, just because I thought it was cool that his phone number had "444" in it. Boy was that a mistake. I got calls from debt collectors for months. =P I still have that number though. Not sure how many years ago that was.. umm.. I think at least 10.