Unfortunately, most carriers (except ATT & Verizon) are just T-Mobile resellers... so you might think you're not using T-Mobile but you're still affected.
Even if you use ATT or Verizon, the article mentions they're also hacked and SMS intercepted often.
Honestly, I’d assume being on a MVNO carrier would actually protect you from this, as you’re simply roaming on the T-Mobile network through the carrier agreement. Even ATT and Verizon have roaming agreements.
The issue is for T-Mobile direct customers, which obviously their internal systems have access to. I see no reason why T-Mobile would have access to users accounts at another company…
"Google says that hackers may have accessed limited customer information via the compromised system, which includes phone numbers, SIM card serial numbers, account status, and mobile service plan data. The system did not contain personal customer information such as names, email addresses, payment card data, government IDs, passwords, or pin numbers."
It depends on the MVNO. Some have their own backends. Others only do the marketing and leave the backend to the carrier.
MVNOs do not roam on the carrier, however. The MVNO has a close direct relationship for wholesale access to the network. Roaming is a wholly separate method of access.
So that leaves Verizon, AT&T, and Dish networks[1]
And all of them have supposedly been compromised, but T-Mobile is the most compromised.
> While it is true that each of these cybercriminal actors periodically offer SIM-swapping services for other mobile phone providers — including AT&T, Verizon and smaller carriers — those solicitations appear far less frequently in these group chats than T-Mobile swap offers. And when those offers do materialize, they are considerably more expensive.
So the choice is, which one is the least compromised, unfortunately
Can you source "most" and define "carrier" specifically for your comment?
Verizon and AT&T are the other of the big 3 carriers in the US, and they're not reselling T-Mobile. And all 3 have MNVOs (mobile virtual network operator) that resell and/or combine the networks of the big 3.
Even if you use ATT or Verizon, the article mentions they're also hacked and SMS intercepted often.