More people than you realize still have landline phones. Curious as to why you believe that 3g is no longer going to be functioning ? Why not contact T-Mobile to inform them of problems? T-Mobile sucks and while I hate Verizon they have the best network.

Go to Walmart phones and it only cost 50 bucks for a phone, you can either get a new number or just forward the T-mobile number to the throw away phones.