Is it possible to recognize and automatically insert into the order form the phone number of a user visiting the site from a mobile device?

Question

Online shopping

Actually, is it possible and how to do it?
It would be convenient: the user simply presses the big order button and after a while the manager contacts him.

Answer 1

Of course not. The user enters the site through the Internet, not a phone number :)

Answer 2

I saw this only once in my life, when I went to the site via a USB modem, and the USB modem number was immediately displayed there with an offer to connect the service to this number, apparently that site had special conditions for cooperation with Megafon. I didn't see it again. So theoretically it is possible but through a cellular operator.