System and method for handing over a call from a packet-switched network to a circuit-switched network

• US 8,437,368 B2
• Filed: 06/04/2003
• Issued: 05/07/2013
• Est. Priority Date: 06/04/2003
• Status: Active Grant

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Krishnamurthi, Govind, Chaskar, Hemant M.
• Primary Examiner(s): Wu, Jianye
• Application Number:
  US10/454,685
• Publication Number:
  US 20040246990A1
• Time in Patent Office: 3,625 Days
• Field of Search: 370/466
• US Class Current: 370/466
• CPC Class Codes: H04W 36/00224 between packet switched [PS] and circuit switched [CS] network technologies, e.g. circuit switched fallback [CSFB]
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

A communications system and method are provided for handing over a call from a packet-switched network (e.g., IP network) to a circuit-switched network (e.g., PLMN, PSTN, etc.). The system includes a first terminal capable of communicating via a packet-switched network and a circuit-switched network, and a second terminal capable of communicating via a circuit-switched network. The system also includes a gateway capable of mapping communications between a packet-switched network and at least one circuit-switched network. The gateway can support communication between the first terminal and the second terminal such that the first terminal has a packet-switched connection with the gateway and the second terminal has a circuit-switched connection with the gateway. The first terminal can then establish a circuit-switch connection with the gateway. Thereafter, the gateway can connect the circuit-switched connection established between the first terminal and the gateway with the circuit-switched connection between the gateway and the second terminal.

Claims

1. A communications system comprising:

a first terminal configured to communicate via a packet-switched network and a circuit-switched network;

a second terminal configured to communicate via a circuit-switched network; and

a gateway configured to map communications between a packet-switched network and at least one circuit-switched network,

wherein the gateway is configured to support communication between the first terminal and the second terminal such that the first terminal has a packet-switched connection with the gateway and the second terminal has a circuit-switched connection with the gateway, wherein the first terminal is configured to thereafter initiate a handoff of communication from the packet-switched network to the circuit-switched network, the first terminal being configured to establish a circuit-switched connection with the gateway, and wherein the gateway is configured to connect the established circuit-switched connection between the first terminal and the gateway with the circuit-switched connection between the gateway and the second terminal to thereby handoff communication from the packet-switched network to the circuit-switched network;

wherein the first terminal is configured to receive a handoff identifier hosted by the gateway, and wherein the first terminal is configured to establish the circuit-switched connection with the gateway based upon the handoff identifier, and

wherein the first terminal is configured to establish the circuit-switched connection with the gateway in an instance in which a signal strength of the packet-switched connection between the first terminal and the gateway is below a predetermined threshold for more than a predefined period of time, and wherein the gateway is configured to connect the circuit-switched connection established between the first terminal and the gateway with the circuit-switched connection between the gateway and the second terminal in instances in which the first terminal establishes the circuit-switched connection with the gateway.

2. A communications system according to claim 1, wherein the first terminal is further configured to transmit a shared secret to the gateway as the first terminal establishes the circuit-switched connection with the gateway to enable the gateway to verify the shared secret before the circuit-switched connection is established with the first terminal.

3. A communications system according to claim 1, wherein the gateway is configured to support communication between the first terminal via a packet-switched network and the second terminal via a first circuit-switched network, and wherein the first terminal is configured to thereafter establish a circuit-switched connection with the gateway via a second circuit-switched network that is different than the first circuit-switched network.

4. A communications system according to claim 1, wherein the gateway is configured to support communication between the first terminal via a packet-switched network and the second terminal via a circuit-switched network, and wherein the first terminal is configured to thereafter establish a circuit-switched connection with the gateway via the same circuit-switched network.

5. A method comprising:

setting up communication between a first terminal and a second terminal over a gateway such that the first terminal has a packet-switched connection with the gateway and the second terminal has a circuit-switched connection with the gateway;

initiating, at the first terminal, a handoff of communication from the packet-switched network to the circuit-switched network;

establishing a circuit-switched connection between the first terminal and the gateway via a circuit-switched network; and

connecting the circuit-switched connection established between the first terminal and the gateway with the circuit-switched connection between the gateway and the second terminal,

wherein establishing a circuit-switched connection comprises establishing a circuit-switched connection between the first terminal and the gateway based upon a handoff identifier hosted by the gateway, and

monitoring a signal strength of the packet-switched connection between the first terminal and the gateway,

wherein establishing a circuit-switched connection comprises establishing a circuit-switched connection when the signal strength of the packet-switched connection is below a predetermined threshold for more than a predefined period of time, and wherein connecting the circuit-switched connection comprises connecting the circuit-switched connection established between the first terminal and the gateway with the circuit-switched connection between the gateway and the second terminal in instances in which the circuit-switched connection is established between the first terminal and the gateway.

6. A method according to claim 5, wherein establishing a circuit-switched connection further includes transmitting a shared secret to the gateway, and thereafter verifying the shared secret before establishing the circuit-switched connection.

7. A method according to claim 5, wherein setting up communication comprises setting up communication between the first terminal via a packet-switched network and the second terminal via a first circuit-switched network, and wherein establishing a circuit-switched connection comprises establishing a circuit-switched connection between the first terminal and the gateway via a second circuit-switched network that is different than the first circuit-switched network.

8. A method according to claim 5, wherein setting up communication comprise setting up communication between the first terminal via a packet-switched network and the second terminal via a circuit-switched network, and wherein establishing a circuit-switched connection comprises establishing a circuit-switched connection between the first terminal and the gateway via the same circuit-switched network.

9. An apparatus comprising,

at least a processor, a memory having computer coded instructions, said instructions, when executed by the processor, being configured to cause the apparatus to:

map communications between a packet-switched network and at least one circuit-switched network,

support communication between a first terminal and a second terminal such that the first terminal has a packet-switched connection with the apparatus and the second terminal has a circuit-switched connection with the apparatus,

receive an indication of the first terminal initiating a handoff of communication from the packet-switched network to the circuit-switched network,

communicate with the first terminal to establish a circuit-switched connection between the first terminal and the apparatus,

connect the circuit-switched connection established between the first terminal and the apparatus with the circuit-switched connection between the apparatus and the second terminal to thereby handoff communication from the packet-switched network to the circuit-switched network,

host a handoff identifier,

communicate with the first terminal to establish the circuit-switched connection based upon the handoff identifier, and

wherein the instructions are further configured to, with the processor, cause the apparatus to;

communicate with the first terminal to establish the circuit-switched connection when a signal strength of the packet-switched connection between the first terminal and the apparatus is below a predetermined threshold for more than a predefined period of time, and

connect the circuit-switched connection established between the first terminal and the apparatus with the circuit-switched connection between the apparatus and the second terminal in instances in which the first terminal establishes the circuit-switched connection with the apparatus.

10. An apparatus according to claim 9, wherein the processor is further configured to receive a shared secret as the circuit-switched connection is established with the first terminal, and wherein the processor is configured to verify the shared secret before the circuit-switched connection is established with the first terminal.

11. A computer program product comprising a non-transitory computer-readable storage medium, having computer-readable program code portions stored therein, the computer-readable program portions configured to perform a method comprising:

setting up communication between a first terminal and another terminal over a gateway such that the first terminal has a packet-switched connection with the gateway and the other terminal has a circuit-switched connection with the gateway;

initiating, at the first terminal, a handoff of communication from the packet-switched network to the circuit-switched network;

establishing a circuit-switched connection between the first terminal and the gateway via a circuit-switched network;

connecting the circuit-switched connection established between the first terminal and the gateway with the circuit-switched connection between the gateway and the other terminal,

wherein establishing a circuit-switched connection comprises establishing a circuit-switched connection between the first terminal and the gateway based upon a handoff identifier hosted by the gateway, and

monitoring a signal strength of the packet-switched connection between the first terminal and the gateway, and

wherein establishing a circuit-switched connection comprises establishing a circuit-switched connection when the signal strength of the packet-switched connection is below a predetermined threshold for more than a predefined period of time, and wherein connecting the circuit-switched connection comprises connecting the circuit-switched connection established between the first terminal and the gateway with the circuit-switched connection between the gateway and the other terminal in instances in which the circuit-switched connection is established between the first terminal and the gateway.

12. A computer-readable storage medium according to claim 11, wherein establishing a circuit-switched connection includes transmitting a shared secret to the gateway to enable the gateway to thereafter verify the shared secret before establishing the circuit-switched connection.