You know how some websites you can access without a data plan or connected to authenticated wifi? They're called zero-rated websites.
Like during Covid a lot of telecoms did this. Like this:
https://newsday.co.tt/2020/03/15/bmobile-zero-rates-12-websites-for-covid19-access/There are VPN tunnel apps where you can create a secure fully encrypted tunnel to a zero-rated website. So the way telecoms know that data is passing is by checking the SNI Server Name Indication for each HTTPS request.
https://www.cloudflare.com/learning/ssl/what-is-sni/You can change the SNI while connected to a zero-rated website. So all the HTTPS calls pass through that host. Free data internet because according to their checks you haven't requested any https to their DNS. It's free to implement too once your know a zero-rated SNI. Like here
https://github.com/topics/internet-filtering Or apps like Ha Tunnel vpn. Or http Injector vpn. Or NapsternetV.
The catch is, a mobile data ISP could probably eventually figure out what you're doing and ban you, your sim card number is linked to your id card they can make your life legally messy for breaking their terms and conditions. And it can get worse because they can label you as a "hacker" and suddenly attract more attention from international authorities (you're on a list now) and even the dark deep interwebz that you didn't even know about. Or maybe nothing will happen and you get free data for free.
