Method, device and system for user authentication

A method of user authentication is disclosed. The method is performed at a server device having one or more processors and memory for storing programs to be executed by the one or more processors. The method includes receiving, from a first terminal device, a service request including identification information of the user. The method includes generating a verification code in response to the service request. The method also includes establishing, based on the identification information of the user, a voice communication with a second terminal device in response to a failure of sending a non-voice message including the verification code to the user in a non-voice communication method. The method further includes sending, during the voice communication and to the second terminal device, a voice message including the verification code such that the user uses the verification code to authenticate the service request at the first terminal device.