If you still haven't replaced your (tdma) analog tracfone, you may be having problems with your signal. Check to see if you have an analog tracfone.
If you do, you will need to get a new Tracfone handset. The coverage for their digital network is different from the analog one. So, you need to make sure you're still within their coverage area.
TDMA stands for time division multiple access and is an older, less powerful technology.
Tracfone says you need to purchase a new phone. However, there have been rumors that they will replace them.
I know one person who had one of those old handsets. The clear plastic covering the screen had turned yellow, but he kept the phone as a point of pride. Anyway, he told me that Tracfone actually sent out a free (though basic) replacement phone to him.
As long as you keep buying minutes, they'd probably prefer to keep you as a customer rather than annoy you with spotty service. However, even if they don't do that for you...