How do you change a mobile phone from T-mobile to Orange network?

I'm on t-mobile and its ****, I want to be on orange instead. But i don't want to change my number or lose any details like phone numbers. Is there any way to do this on the internet? Tar innit x|||T-mobile and Orange are about to merge and be one company so it won't be longtime. (Another useless peice of information bought you by U.G





I guess the thing to do here is contact you network provider T mobile and then ask Orange or perhaps visit their website