Browse Prior Art Database

Call forwarding improvement in VCC Solution

IP.com Disclosure Number: IPCOM000173688D
Original Publication Date: 2008-Aug-20
Included in the Prior Art Database: 2008-Aug-20
Document File: 4 page(s) / 510K

Publishing Venue

Motorola

Related People

Shivakumar Venkataraman: INVENTOR [+5]

Abstract

In an IMS-based network providing Voice Call Continuity (VCC) for dual mode handsets, the VCC server is responsible to route the call to the subscriber after determining whether the subscriber is in the Circuit Switched (CS) or the Packet Switched (PS) domain. The call is routed towards the network where the subscriber is currently registered. The network also typically hosts a Feature Server (FS), which is an application server providing telephony features to subscribers in this network. To allow the call to be anchored at the VCC server, it is the last application server to be invoked during call termination; after the FS node is invoked. It is the VCC server that, based on the termination subscriber's presence, routes the call in the PS or the CS domain. As a result the FS has no way of knowing that the call is routed towards the CS domain by the VCC server and hence may need more time for presenting the call to the user. This results in the FS being unable to appropriately manipulate the 'No Answer' timer for the purpose of offering the Call Forwarding service uniformly. It may even result in a situation that the termination attempt is cancelled by the FS much before the termination Mobile Station (MS) is paged in the CS domain (by the Mobile Switching Centre (MSC)). This paper details a solution wherein the VCC server informs the FS when the call is routed towards the CS domain. The FS, with the use of this information, can stop the 'No Answer' timer resulting in a unified experience to the end user with regards to call delivery in the PS or CS domain.

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Call forwarding improvement in VCC Solution

By Shivakumar Venkataraman, Deepak Gandotra, Anjum Jeelani, Manisha Gupta, Srinidhi N

Motorola, Inc.

Core Networks Division.

 

 

ABSTRACT

In an IMS-based network providing Voice Call Continuity (VCC) for dual mode handsets, the VCC server is responsible to route the call to the subscriber after determining whether the subscriber is in the Circuit Switched (CS) or the Packet Switched (PS) domain. The call is routed towards the network where the subscriber is currently registered. The network also typically hosts a Feature Server (FS), which is an application server providing telephony features to subscribers in this network.

To allow the call to be anchored at the VCC server, it is the last application server to be invoked during call termination; after the FS node is invoked. It is the VCC server that, based on the termination subscriber’s presence, routes the call in the PS or the CS domain. As a result the FS has no way of knowing that the call is routed towards the CS domain by the VCC server and hence may need more time for presenting the call to the user.

This results in the FS being unable to appropriately manipulate the ‘No Answer’ timer for the purpose of offering the Call Forwarding service uniformly. It may even result in a situation that the termination attempt is cancelled by the FS much before the termination Mobile Station (MS) is paged in the CS domain (by the Mobile Switching Centre (MSC)).

This paper details a solution wherein the VCC server informs the FS when the call is routed towards the CS domain. The FS, with the use of this information, can stop the ‘No Answer’ timer resulting in a unified experience to the end user with regards to call delivery in the PS or CS domain.

PROBLEM

The VCC server is responsible for routing the termination call towards the subscriber based on the knowledge about where the subscriber is currently registered. The subscriber can be registered in the PS domain or the CS domain or both. In such a scenario the VCC server knows where to reach the subscriber. The FS provides the subscriber with services and also runs the ‘No Answer’ timer for the call. In case the termination does not answer the call within the ‘No Answer’ timer duration then the FS shall cancel the call.

There are times when the subscriber is registered in both the PS and CS domain and due to poor PS signal strength can only be reached in the CS domain. In such a scenario the termination attempt, by the VCC server, would first be made in the PS domain and then in the CS domain.

There is a time lag between the attempt in the PS domain and the attempt in the CS domain. This is the time it takes for the VCC server to determine that the subscriber, though registered in the PS domain, is not reachable there and the call needs to the re-routed tow...