Circuit-switched and multimedia subsystem voice continuity with bearer path interruption

Abstract

The present invention maintains calls during transfers between different types of subsystems, even when there is a bearer path interruption at the user element due to the original connection from the transferring-out subsystem being dropped before the new connection in the transferring-in subsystem is established. The call signaling leg toward the remote endpoint of the remote party is held, while the call signaling leg toward the user element is moved from the transferring-out subsystem to the transferring-in subsystem and a new bearer path is established via the transferring-in subsystem. During transfers with a bearer path interruption, a portion of the bearer path leading to the remote endpoint may be connected to a media resource function, which will provide an announcement to the remote party. Once the user element is accessible in the transferring-in subsystem, the bearer path is further transferred to the user element via the transferring-in subsystem.

Description

[0001] This application claims the benefit of U.S. provisional patent application 60 / 685,645 filed on May 27, 2005, the disclosure of which is hereby incorporated by reference in its entirety.FIELD OF THE INVENTION [0002] The present invention relates to communications, and in particular to providing a continuity control function for supporting calls over circuit-switched subsystems and packet subsystems, as well as effecting transfers of established calls from one subsystem to another. BACKGROUND OF THE INVENTION [0003] Packet communications have evolved to a point where voice sessions, or calls, can be supported with essentially the same quality of service as that provided by circuit-switched communications. Packet communications are generally supported over packet subsystems, which were initially supported by local area networks, but are now supported by wireless local area networks (WLANs). Using WLAN access, user elements can support voice sessions using packet communications w...

AI Technical Summary

Benefits of technology

[0008] Call control for originating and terminating calls in a circuit-switched subsystem (CS) or a multimedia subsystem (MS) as well as transferring calls between the CS and MS is anchored at a continuity control function (CCF) in the MS. Call signaling for the call is generally passed through the CCF. The CCF is a service provided in the user element's home MS and anchors the user element's active CS calls and MS sessions to enable mobility across the CS and MS while maintaining voice calls and related sessions.

[0009] The CCF is configured to maintain calls during transfers between subsystems, even when there is a bearer path interruption at the user element due to the original connection from the transferring-out subsystem being dropped before the new connection in the transferring-in subsystem is established. The bearer path interruption

Problems solved by technology

The bearer path interruption may result in a pe

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