Don't worry it's a common problem I'll give you details below how to fix it.
1. check your apple ID is linked to your transferred number. Correct if necessary and save the changes.
2. Settings > FaceTime > FaceTime > OFF
3. Settings > Messages > iMessage > OFF
4. Settings > Messages > iMessage > ON
Your phone shoud now set up your correct number. Verify this has happened:
Settings > Messages > Receive At > Phone
Settings > Phone > My Number
5. Settings > FaceTime > FaceTime > ON
6. Turn your iPhone off and back on and resync to iTunes.
You can check your apple ID here.https://appleid.apple.com/