The difference is its free to change you card (At least for my bank it is) where as getting a phone number isn't. And like the guy who mentioned the phone vendor... they'd have to drive there, fill out paper work just to make a new account. If that same guy gets banned again he'd go back there and fill again more paper work etc. Major hassle for the hacker if its phone verification.
Dude, I can call my phone company and have my number changed whenever I want for FREE. I can also go to Walmart and buy a surplus of throwaway phones for under $10 each. I can also go with a prepaid phone company that has no contract EVER. I am not even a hacker and I can do all these things.
Not available at here, the phone number need your IC number, except you are buying with unnormal way. And we only can switch the provider with the same number or buy a new number.