You want to give your phone number to someone you just met. The humans have to exchange the digits by talking or typing. One phone should display a QR the other phone scans and the phone number gets inserted into contacts just like that.

i.e. the QR should have all the info of a VCard:

https://en.wikipedia.org/wiki/VCard

I've googled around and found stuff like:

https://flexibits.com/cardhop

https://www.scanbizcards.com/

but it should be much easier. In iOS the wallet app should have several vCards of your self. You want to give someone your main cell number + name + email that's one wallet item. You want to give someone just your google voice number + name and no email that's another.

And built into iOS and Android should be if the camera scans these it knows to auto insert into contacts. We use QR's for everything else! Why are we still printing business cards to be scanned or giving out a 10 digit number by speaking?