Google added a new Admin console option for G Suite admins designed to help them disable telephony options as two-factor authentication (2FA) methods. 2FA requires users to verify their identity through something they know (such as a password) plus something they have plus a physical key or access code delivered to a device. Google recommends businesses to use security keys as part of their 2FA process, and the Google Authenticator app as more secure alternatives when compared to phone-based verification methods. The new policy is available to all G Suite editions but they will not be enabled by default.
Source: https://www.bleepingcomputer.com/news/security/google-now-lets-g-suite-admins-disable-insecure-phone-2fa/