How to fix iOS7 iMessage and FaceTime (phone number) activation issue
There seems to be a lot of people with iMessage and FaceTime issues (likely since iOS7 and the iPhone 5S were released). I pretty much tried everything on the Apple Support site, and whatever I could find published on the web. Nothing seemed to work 100% of the time (or at all in some cases).
It seems to me to be an activation issue. Logic says that your registered iCloud / Apple ID phone number needs to match the phone number of the device you are activating from. Logic prevails...I've checked this fix using different Apple ID's and it seems to work perfectly.
Simply follow these steps to fix iMessage and FaceTime activation issues:
1. Switch OFF iMessage and FaceTime on your iOS device
2. Log in to Apple's "Manage your Apple ID" site (https://appleid.apple.com/)
3. Click on the "Phone Numbers" option
4. Replace the "1" in the "Country Code" field with your local country code (if you don't know it check online here: http://countrycode.org)
5. Put in the phone number of the device you are trying to activate (Note: I'm not sure which field Apple validate against in iOS7 so just update them all)
6. Switch ON iMessage and FaceTime on your iOS device
Voila! All good for me on many devices with different phone numbers, using different Apple ID's. Hope that helps.
iOS 7