So since updating my Sprint iPhone 5s to iOS 8, i've been having this random issue with iMessage. Randomly when messaging my wife's iPhone, the iMessage will fail to send. However, it will not auto retry as SMS. Even hours later. I have to manually select the message and choose to send it as an SMS message which goes through just fine. Any subsequent iMessage after the SMS message is sent goes through just fine. If my wife sends me an iMessage after my message fails to send all subsequent messages go through just fine. My wife does not have this issue with her iPhone. I only have the issue with her iPhone. I have gone through Apple support and went through all the troubleshooting steps and yet the problem still occurs. This is quiet frustrating when I need to send a time sensitive message and find out it never went through. Any suggestions?