You could use privacyIDEA, which is a two factor auth server and is also capable of sending SMS via HTTP gateways. BUT: You would rather want to use 2nd factor

You could use privacyIDEA, which is a two factor auth server and is also capable of sending SMS via HTTP gateways. BUT: You would rather want to use 2nd factors like HOTP or TOTP token or a yubikey.