It's a Sprint issue, not an Evo issue. I'm not a real big texter but my kids have complained about this many times, and they've never had Evos (or any other smart phone).
I never had this problem with sprint before my Evo
This happens when you are roaming. If you turn the roaming off, the issue will stop. I did this with my Hero and now with my EVO. Of course, you won't have service sometimes, but you can pick your poison.
