Are you having a problem when sending a message using iMessage in iOS 7? I have a few days with this problem and had to restart my iPhone so ican send them properly, something I find quite annoying, plus they last a while, I have the same problem again .
If you have this same problem, this is how to Fix iMessage Error on iPhone 5S with iOS7 :
- Disable iMessage from Settings -> General -> messages.
- Reset the network settings in Settings -> general -> reset.
- Activate iMessage from Settings -> General -> Messages.
With these steps in theory would have to run smoothly, but if you will not do this (as it would lose your keys saved Wi-Fi), you can try to reset the device, but as I say, in my case the restart function during few minutes, then stop.