Techniques for granting access on a network having a network service to a user of a mobile device having a microphone includes determining a first identification uniquely associated with a registered user having a registered voiceprint that matches a voiceprint of the user of the mobile device. A second identification uniquely associated with the mobile device is also determined. It is then determined whether to grant access based on the first identification and the second identification. If it is determined to grant access, access is granted on the network to the user. Various aspects of the invention allow a user to be authenticated separately of the mobile device by the voice of the user, and granted access to a network service based on both the user's identity and the identity of the mobile device. Both the user's voice and the device identity are provided using the current capabilities of wireless telephones. Obtaining the first identification and second identification within a specified time interval makes confidently practical the technique of verifying that a certain user controls a certain mobile device, and then allowing access by that device to protected services.