How can an online store receive information about the location of the client?

Question

Geolocation

Hello.
A person lives in city A. A person came to city B, bought clothes there in a YYY store, purchased a discount card (as usual, indicating a phone number). He came home to city A. Then he went to city B, and there he receives an SMS with information that there is a sale in the YYY store in X mall. Shopping center X is only in city C, it is definitely not in city B, where he bought things.
Excluded information transmission channels:
- geolocation through the site (there was no authorization, there was no indication of a phone number there, there were no visits to the site at all)
- geolocation through the application (it was not installed).
There was no contact with the store through electronic means, where an identifying feature in the form of a telephone could be transmitted.
iOS phone.
How could location information get into the store?
PS I want to have the same feature. Perhaps these are Google services: advanced analytics is installed on the site, and a person uses Google at home, and uses Google on a trip, he catches a change in location and ... and what's next, how and at what stage this information is tied to a phone number and gets into score?
The only thing that comes to mind is the transmission of the Phone Number / Base Station bundle from the mobile operator to all those who have connected any service.

Answer 1

https://target.my.com/adv/dmp/begin_for_data_owner/