It seems to me that one of the problems with Sprint Direct Connect ("SDC") is that it is not given the highest interrupt priority on the handsets. I'm not stating this as fact, I'm thinking out loud while trying to figure out why SDC works very well some of the time and is horribly unreliable other times.

What we have noticed is that any time our Kyocera Torques went to standby mode without first pressing the Home button, PTT calls can't reliably get through. If the last thing one of us did was read a text message, then set the phone aside and let it go to standby mode with the text application still "open", even when both phones have decent 3G signal, we consistently get the "user unavailable" #310 or #320 error messages, and PTT refuses...
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