How is SMS a security risk? As far as I know, SMS is closely tied to a person's identity, especially 'know your customer' regulations. I'm curious how it's a security risk; as far as I know they have to be unique, which is good
But if the attacker already has your info, then couldn't they just add another line to your mobile plan, so your handset continues working, just with a new, unbeknownst to you phone number? That way it wouldn't be noticable on the handset.
The real question is how long do you think it would take you to break into your own Gmail account after the passwords been changed and the attached phone numbers also been changed?
Probably longer than it would take an attacker to drain bank accounts, I figure.
Moreover, you don't want it to be tied to your identity. The fact that anyone can pretend to be you and hijack your phone number is exactly what makes it insecure.
Or, you know, they can just bribe the store employees. Has happened before, still happens, will keep happening as long as a phone number is considered important for anything at all.