I've been unable to activate iMessage on my iPhone 5s for the past few hours. I have tried using 3 different Apple IDs and I get the same error. A "Waiting for activation..." message appears, and then "Could not sign in. Please check your network connection and try again" appears a moment later after sign in fails. Restored my phone and tried again, and its still doing it. Anyone else? Seems like iMessage isn't working for a bunch of people on twitter too, curious how widespread it is.