I'm on TMO in the US and haven't ditched it yet for the same reasons. I just take all possible precautions. Namely, never use your TMO phone number for any ki

I'm on TMO in the US and haven't ditched it yet for the same reasons. I just take all possible precautions. Namely, never use your TMO phone number for any kind of 2FA on other services. Use TTOP, Yubi, and if those aren't available on a particular service then Google Voice for SMS 2FA. If GV isn't allowed, then obfuscate your username, password, and disable account recovery on that service, among other precautions (or just don't use that service at all, find a replacement).