My cell service provider was like that up till earlier this year. As soon as they made it possible to switch from prepay to a per-month contract without changing my number, I did it. And this was after years of asking every few months when they were going to make the service available.

I've had the same cellphone number since 1999. I wasn't in any hurry to change, but I thought the policy was absurd and considered it worth letting them know that I was staying with them in spite of it, rather than because of it or being indifferent to it.