Starting next week Google will overhaul its two-step verification (2SV) procedure and replace one-time codes sent via SMS with prompts shown on the user’s smartphone. The change in the Google 2SV scheme comes after an increase in SS7 telephony protocol attacks that have allowed hackers to take over people’s mobile phone numbers and break into user accounts. Google says it will re-invite users to join the mobile prompt program after six months. Users can decline Google’s invitation to use mobile prompts and continue to use SMS codes.
Source: https://www.bleepingcomputer.com/news/google/google-to-replace-sms-codes-with-mobile-prompts-in-2-step-verification-procedure/