SMS is not suitable for 2FA. It has a massive "help desk" hole that is obnoxiously easy to exploit. SMS is only useful as a proof of stake, IE something you do to initially set up a second factor to prove that you have some skin in the game, but not as the second factor itself. Honestly, even that proof of stake stuff is separate from setting up 2FA, it's mostly about slowing down botnet signups.
There are times where SMS 2 factor is worse than no 2 factor at all. Common number porting attacks allow an attacker to be far more convincing to the support staff when they call to say that they forgot the password but still have access to the second factor.