Login.gov Error: "This Phone Number Cannot Be Verified"

Error Code: PHONE_CARRIER_UNSUPPORTED / VOIP_RESTRICTED

Fix for non-US phone numbers, Google Voice, Skype, and VOIP numbers being rejected during Login.gov two-factor authentication setup.

Step-by-Step Resolution Protocol

Select "Authentication application" instead of "Phone" during 2FA selection.
Scan the QR code with Google Authenticator, Microsoft Authenticator, or 1Password.
Alternatively, select "Security Key" (YubiKey / WebAuthn passkey) to log in instantly using biometric Face ID or Touch ID on your device.
Download and print the 16-character Login.gov personal key in case you ever lose your phone device.