[Home](./index.md) > [@firebase/auth](./auth.md) > [PhoneMultiFactorAssertion](./auth.phonemultifactorassertion.md) ## PhoneMultiFactorAssertion interface The class for asserting ownership of a phone second factor. Provided by [PhoneMultiFactorGenerator.assertion()](./auth.phonemultifactorgenerator.assertion.md). Signature: ```typescript export interface PhoneMultiFactorAssertion extends MultiFactorAssertion ``` Extends: [MultiFactorAssertion](./auth.multifactorassertion.md)