Q: Can not use FaceTime

There is some troubleshooting at the bottom of this page : http://support.apple.com/kb/HT4319

If that doesn't help, then if you give more info somebody on here might be able to help - I assume that both you and the person that you are trying to call are on wifi ?

You need to create a FaceTime account using youre apple I'd.

You may also be sending a FaceTime to an unregistered FaceTime user.

I think your network speed is low. Maybe you should try DNS settings 8.8.8.8

The Complete Guide to FaceTime: Set-up, Use, and Troubleshooting Problems

http://tinyurl.com/32drz3d

 Cheers, Tom