Transferring Phone Number to a New Unactivated Phone

I bought a new phone to replace my unusable broken one. To activate this phone, I need to transfer my phone number, however I cannot transfer the phone number from my old phone to this new one without activating it... so I'm stuck in a bit of a paradox... I'm not sure what to do. How do I transfer my old Phone number, still on my at&t account, to this New phone to activate it / add it to my devices on my plan?

This new device has a new sim card and the old one's sim card is unreachable.