IPhone says that it has no number?

I received a new iPhone in the mail and switched all of my data to it. However, although the new one has service, it says that it has no number. So my old iPhone is receiving all of my texts and calls.

What should I do? Or will my number be transferred to the new phone once I send the old one back to Verizon?

You need to have the switch done in the store- or you will have a nice brick.