I bought her a new phone. But it is a different model and Julie is stubbornly resistant to change, so she ended up stealing her mother's phone, which is identical to her old one. Fine.
Except we had the wrong numbers attached to the phones. Oh, and our provider is Ting and the old phone has service from Sprint, while the new phone has service from Verizon.
After a couple of chat sessions this afternoon, numbers have been swapped between the phones and all is again right with the world.
tl,dr: If you call Gretchen's cell phone number, you will now get Gretchen instead of Julie. :)