Circuit-switched and multimedia subsystem voice continuity
AssigneeEricsson Inc.
InventorsKaniz Mahdi, Dany Sylvain
Life of this patent
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Abstract
The present invention moves service control, including call control, for a user element from a cellular network to a multimedia subsystem (MS), such as the Internet Protocol (IP) Multimedia Subsystem (IMS). Call control is provided by the MS irrespective of whether the user element is using cellular or WLAN access for the call. Call control for originating and terminating calls in the CS or MS as well as transferring calls between a circuit-switched subsystem (CS) and MS is anchored at a continuity control function (CCF) in the MS. All call signaling for the call is 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 active roaming across the CS and MS.
Claims27
A method of operation of a continuity control function, comprising:
- providing a signaling anchor point in a multimedia subsystem for a first access signaling leg and a remote signaling leg for a call between a user element and a remote endpoint, the first access signaling leg established between the signaling anchor point and the user element for the call via a transferring-out subsystem, and the remote signaling leg established between the signaling anchor point and the remote endpoint;
- establishing a second access signaling leg towards the user element via a transferring-in subsystem;
- replacing the first access signaling leg with the second access signaling leg, such that the second access signaling leg is anchored at the signaling anchor point;
- and
- providing call signaling via the second access signaling leg and the remote signaling leg to transfer at least a portion of a bearer path connected to the user element from a first network to a second network;
- wherein, when the call is originated from the user element, the continuity control function appears as a service provided by an application server and is invoked as a first service of a chain of services associated with the call, such that all of the services associated with the call other than the continuity control function are anchored by the continuity control function as part of the remote signaling leg of the call;
- and
- wherein when the call is terminated at the user element, the continuity control function is invoked as a last service of a plurality of services to be provided in a call signaling path formed by the first access signaling leg and the remote signaling leg, such that all of the plurality of services other than the continuity control function are provided in the remote signaling leg, and the remote signaling leg is anchored at the continuity control function.
A node operative to provide a continuity control function, comprising:
- a communication interface;
- and
- a control system associated with the communication interface and operative to:
- provide a signaling anchor point in a multimedia subsystem for a first access signaling leg and a remote signaling leg for a call between a user element and a remote endpoint, the first access signaling leg established between the signaling anchor point and the user element for the call via a transferring-out subsystem, and the remote signaling leg established between the signaling anchor point and the remote endpoint;
- establish a second access signaling leg towards the user element via a transferring-in subsystem;
- replace the first access signaling leg with the second access signaling leg, such that the second access signaling leg is anchored at the signaling anchor point;
- and
- provide call signaling via the second access signaling leg and the remote signaling leg to transfer at least a portion of a bearer path connected to the user element from a first network to a second network,
- wherein, when the call is originated from the user element, the continuity control appears as a service provided by an application server and function is invoked as a first service of a chain of services associated with the call, such that all of the services associated with the call other than the continuity control function are anchored by the continuity control function as part of the remote signaling leg of the call;
- and
- wherein when the call is terminated at the user element, the continuity control function is invoked as a last service of a plurality of services to be provided in a call signaling path formed by the first access signaling leg and the remote signaling leg, such that all of the plurality of services other than the continuity control function are provided in the remote signaling leg, and the remote signaling leg is anchored at the continuity control function.
Dependencies are inferred from the claim text.