Since the release of iOS 7, many users have been reporting issues with iMessage not receiving or sending messages. Some users are even reporting that their messages are being marked as sent, only to have them pop up as failed several hours after sending.
There have been a few workarounds, with the most popular simply being to restarting the device. Other fixes include resetting the network settings, or even resetting the phone all together. None of these settings seem to fix the issue for more than a few minutes which indicated that the issues are on Apple's end. Luckily, the company says that it is working to fix the issue.
"We are aware of an issue that affects a fraction of a percent of our iMessage users, and we will have a fix available in an upcoming software update," Apple said in a statement.