Hey I had the same problem and there is such a simple fix to it.

1. Turn on Airplane Mode - You will notice that you can not access your phone settings while airplane mode is on.

2. Turn off Airplane Mode and Immediately go to your phone settings and click on the unknown number tab and you will be able to manually enter your number. After this you should also get a message from imessage saying that you might be charged some amount or something like that. Say okay and you are all set to go. Hopefully this helps for regular messaging also, my regular messaging was already working only imessage was going through my email and not as my no. Enjoy!!!

are u sure? your phone sets is local set? or not?
i read in some forum they said this also can fix it.

1. Create a contact with your name, phone number, mail, etc. (I used the format "+ Country_Code + Area_Code + phone_number"). Really the format doesn't matter (I guess).

2. Go to:

- "Settings"

- "mail, contacts calendar..."

3. Search for the group "Contacts"

-Select "my data"

-Select the contact you have created in step 1.



That's all !!!!

please do more research on google there is many solution there.

your phone is local set?