As a developer, I reported this problem with video to back it up showing them what happens between two phones with iMessage and was told by engineers that this is normal behavior. Hmmm guess they should have paid more attention to me 2 months ago.
Will resetting network settings lose all my known Wifi's?
My fix was to change my iCloud password.
This has been happening to me on and off again since I downloaded GM build. Still happens now that I'm at 7.0.2. Very frustrating that it doesn't fall back to regular text messages.
I just had to restart my iphone. Then it worked again.
But some iMessages never got thru to me. I know, they were from my wife.
I had issues last night. I'm on 6.1. People on iMessages suddenly turned green, messages failed. Mine were sent to an iPad, so SMS fallback wasn't an option. Don't know if the stats in post #1 looked at that.Too glad I'm still on iOS 6
Good grief. I thought I was going insane. My wife's iP4S has been having this issue and it was driving me crazy. Power cycle clears it temporarily.
Another thing - we use a single Apple ID as both iTunes and iCloud account across 5 devices (I know, that's not what you're supposed to do but it is required to track/manage all devices in one FindMyIphone session).
My wife's phone constantly gets confused about where to deliver iMessages despite selecting only her cell number. The phone just randomly adds back in a second device cell number from our group of 5. This happens only on her iP4S.