Can't enable iMessage on iPhone 6
I have an iPhone 6 and a while ago it stopped sending iMessage. I went to settings to try and enable it, but the switch was greyed out. I still receive iMessage, but they take a couple of days to sync from the cloud. Was iMessage disabled for older iPhones? Or is this a problem with my phone specifically? If so, can I do anything to fix it?
iPhone 6