After I upgraded to iOS 7 on my iPhone 5 I ran into a really annoying problem. Whenever I would send iMessage messages to friends and family the message would look like it’s sending and then the progress bar along the top would stop about 1/4 inch from the end and just stay there for hours. Never sending the message. I tried the Kung-Fu Grip to only partial avail. The solution is to reset the network settings on the iPhone:

Tap Settings
Tap General
Tap Reset
Tap Reset Network Settings

Once the phone resets, and you reset your Wifi and turn on all the cellular bits, like voice and data roaming (at least for me) then after that, everything works as it should.

If this helps you, please let me know. 🙂