Abstract: Application layer authentication of a data-network based application makes use of a SIM function accessible to the application and telephone network authentication service accessible to a server to the application. For example, the application uses SIP (Session Initiation Protocol) for communication with the server and the authentication service is provided via a GSM based telephone network. In one implementation, a device (a “dongle”) includes an authentication module, application software, and an interface for communicating with a remote server over a data communication network. The application software includes instructions for using the authentication module to authorize an application layer interaction with the remote server.

Abstract: In one aspect, a communication system allows telephone users to roam between cellular and broadband domains and obtain equivalent level of service and features in the broadband network as in the cellular network. For example, such users can make use of Push-To Talk service, as well as continuous telephone call service, independent of which domain they are connected through. In another aspect, users can pass messages, including voice messages, or establish two-way voice communication between disparate push-to-talk (PTT) or messaging and/or voice systems. For example, a user on a cellular network using a PTT service is able to communicate with a user on a data network using an IM service. In addition, information is passed between the systems to provide coordinated presence information for users. For example, a user can have presence information in multiple networks enabling users form different networks to communication with that user.

Abstract: A telephone system supports communication with user devices over both a cellular radio network as well as over an Internet Protocol (IP) network, and enables roaming and active call handoff between cellular and IP domains. Approaches to detecting presence of a user near a suitable IP network are used in controlling transitions between the domains, for example, enabling automatic transitions between domains, and delivery of calls to a mobile user to data network devices in the vicinity of the user.