There's a question, if you downloaded Uber with a domestic Chinese phone number but are using a US AT&T card in the US, then which number should the driver call? If it's a domestic number, how should it be dialed after the card has been changed ?

There is indeed a problem with making phone calls, but we are all waiting on the street, looking for cars. Don't move around and change the place to wait for the car, so there is no problem with making phone calls.

You don't need to make a phone call.