See if any of these links help your situation --
Using FaceTime http://support.apple.com/kb/ht4319
Troubleshooting FaceTime http://support.apple.com/kb/TS3367
The Complete Guide to FaceTime + iMessage: Setup, Use, and Troubleshooting
Troubleshooting FaceTime and iMessage activation
http://support.apple.com/kb/TS4268
Using FaceTime and iMessage behind a firewall
http://support.apple.com/kb/HT4245
iOS: About Messages
http://support.apple.com/kb/HT3529
Set up iMessage
http://www.apple.com/ca/ios/messages/
Troubleshooting Messages
http://support.apple.com/kb/TS2755
Setting Up Multiple iOS Devices for iMessage and Facetime
http://macmost.com/setting-up-multiple-ios-devices-for-messages-and-facetime.htm l
FaceTime and iMessage not accepting Apple ID password
Unable to use FaceTime and iMessage with my apple ID