I used to work for a T-mobile authorized dealer for years and have been a very satisfied customer over the past 6+ years i've had the service. I recently ported my number out just to save money - my family has a family plan on another carrier and told me if i join their plan i would only have to pay 40 a month (it was an add on line.)
So I call T-mobile customer service and one rep tells me that in Dec. 2011 that the contracts started stating that you will be responsible for paying the full month when porting out. I signed my contract in 2009. He says ok and calculates what my prorated bill should be and says he needs to put me on hold to get it approved - he never comes back to the line = I waited for 40 minutes! i call from my another phone to another rep and he tells me the original rep put in the notes about how i still signed my contract which says "terms and conditions are subject to change." Why not just click over back to me and tell me that?
So "terms and conditions are subject to change" can mean they can do whatever they want and you'll have to pay. A tmobile salesman told me personally that's unfair because they can put me on a 20 year contract and say "terms and conditions are subject to change."
Another rep told me tmobile should have told me that I would be charged for the whole month. But they still couldn't do anything for me.
I had great service over the years with tmobile and sold many lines to my friends and family while working for them but I thought I would warn you about this porting incident / terms are subject to change.
Use your phone until your bill cycle to get your months worth. And beware terms can change without them telling you and you will have to pay for it!
I have no reason to make any of this up. Tmobile can check the recorded phone calls to see how long the rep but me on hold and the false information they told me.