Facetime, iMessage and Push Notifications were working fine on my iPhone 4.
Since I upgraded to iOS 7.0.3 Facetime and iMessages cannot be activated because of 'Network error' and every app that supports 'Push Notifications' suggest to 'Connect to iTunes to use Push Notifications' at start.
Already tried to 'Reset as new phone' and restore from iCloud without any luck.
This worked for me:
After upgrade to iOS 7.03, iMessage, Facetime and push notifications stopped working. iMessage and Facetime displayed the "waiting for activation" message but never activated.
1. iMessage and Facetime turned on
2. turn off wifi
3. turm off iphone
4. turn on iphone
5. turn on iMessage
6. wait a few seconds and you will be prompted for icloud userid amd password - enter your credentials
7. wait a couple of minutes and iMessage and Facetime will be activated and you are back in iBusiness.
Hope it works for someone eles!