Hi,
I use GrapheneOS with no carrier, just VoIP numbers, which is fine as long as I have an internet connection. But I need mobile broadband for when I have no wi-fi. Michael Bazzell suggests using a data plan in his book. Now, there's no such a thing in my country but I can subscribe to Silent.Link, which does the same. The thing is, I don't understand how using mobile broadband is different from using a regular phone number from a carrier, as both use GSM towers and stuff.
tl;dr
What should I know before purchasing a data plan?
I'm not comfortable with carriers knowing and keeping stuff about me for God knows how long.