[Home](./index.md) > [@firebase/auth](./auth.md) > [IdTokenResult](./auth.idtokenresult.md) > [signInSecondFactor](./auth.idtokenresult.signinsecondfactor.md) ## IdTokenResult.signInSecondFactor property The type of second factor associated with this session, provided the user was multi-factor authenticated (eg. phone, etc). Signature: ```typescript signInSecondFactor: string | null; ```