My iPhone 6 iMessage won't turn on after I reset it. I have tried resetting the whole phone it's self & the network settings numerous of times, but it always says "Could not sign in. Please check your network connection & try again". Everything is up to date & I still have about 5 GB's left. I don't know what else to do.
iPhone 6, iOS 8.3
Have you read this:
If you get an error when trying to activate iMessage or FaceTime - Apple Support
There is also a thread over on the iPad forum several pages long where others are experiencing the same issue. Read through the thread as there are several solutions offered that may resolve your problem.
imessage and Facetime sign in activation error iPad ios8.1.2
iMessage won't turn on
