The US National Institute for Standards and Technology (NIST) has announced that it no longer considers text messages as secure enough when used as part of a two-factor identification method (2FA).
Currently, when you opt to use 2FA on your iPhone or iPad, you can choose to have a code sent to you via SMS. That is set to no longer be the case, however, as NIST is soon to bar its use.
9to5 Mac notes that while NIST’s guidelines are not enforceable by law, most companies do usually choose to obey their rulings, so that could mean that Apple will soon drop SMS authentication from its list of options for 2FA, which currently include a phone call to a trusted number, a code sent by SMS to a trusted number, or a code sent to a trusted device such as an iPad, iPhone, iPod Touch, or Mac.
Source: Apple & others may soon be barred from using SMS for two-factor authentication