How does the phone number of the SIM card used to access the Internet get to the content provider?

Question

Beeline

Briefly, background:
A paid subscription has appeared on the SIM card, which is in the modem and is used exclusively for connecting to the Internet. Beeline representatives explained that the subscription appeared because someone went to the website of the subscription provider (a third-party provider, not Beeline) and signed up for a paid service. Beeline representatives claim that since the entrance to the site with a paid service was carried out using a SIM card, they cannot return the money.
Now the questions:
I understand that the phone number from which the Internet is accessed is known to Beeline, but how does this phone number go further and get to the portals to which the connection is made via the Internet?
How can I subscribe to a paid service for a phone number without entering the phone number and doing nothing on the phone itself to confirm the subscription to the service?
How to explain to Beeline representatives that they have a security hole and steal money from subscribers? (unless it's affiliated structures stealing)

Answer 1

How can I subscribe to a paid service for a phone number without entering the phone number and doing nothing on the phone itself to confirm the subscription to the service?

isn't it? https://securelist.ru/blog/issledovaniya/28882/sta...