I think it's more likely the problem is in your phone(s), not T-Mobile's network, because if it was in the network chances are many people would experience this

I think it's more likely the problem is in your phone(s), not T-Mobile's network, because if it was in the network chances are many people would experience this problem. Easiest way to troubleshoot would be for one of you to move your SIM to a different phone for a few days and see if the problem persists. It may not be an issue of "keeping copies" so much as reusing the same space in memory, which every device does. It's pretty easy to imagine a bug that would result in an "end of message" flag being not written or not read/recognized, leading to old data being presented as new data. That's basically the same "buffer overrun" problem that plagues a lot of software developers worldwide. See http://en.wikipedia.org/wiki/Buffer_overflow http://en.wikipedia.org/wiki/Buffer_overflow . The problem can be solved, but first someone must believe that it exists.