Method for setting up a data connection between terminal devices

1. A method for setting-up a data connection between a first terminal device connected to a first connection controller and a second terminal device connected to a second connection controller, comprising:

establishing signaling connections from the first terminal device to the first connection controller, thence to at least one intermediate controller, thence to the second connection controller;

transmitting a setup message comprising first useful data parameters comprising address information specific to the first terminal device from the first terminal device to the second connection controller over the established signaling connections;

storing the first useful data parameters in the second connection controller;

transmitting the connection setup message without the first useful data parameters from the second connection controller to the second terminal device;

transmitting an acknowledgement message from the second terminal device to the second connection controller;

setting-up a direct connection between the second connection controller and the first connection controller, bypassing the at least one intermediate controller;

transmitting second useful data parameters comprising address information specific to the second terminal device from the second terminal device to the first terminal device via the direct connection;

setting-up a first unidirectional connection from the first terminal device to the second terminal device via the first and second connection controllers, bypassing the at least one intermediate controller;

transmitting the stored first useful data parameters from the second connection controller to the second terminal device;

setting-up a second unidirectional connection from the second terminal device to the first communication device via the first and second connection controllers, bypassing the at least one intermediate controller; and

transmitting useful data bi-directionally between the first and second terminal devices using the first and second unidirectional connections,

wherein a media server is connected to one of the connection controllers, and wherein a preliminary data connection is set up between the media server and the first terminal device during initial connection setup signaling.

2. The method as claimed in claim 1 , further comprising indicating an incoming connection by the second terminal device.

3. The method as claimed in claim 1 , wherein a connection acceptance acknowledgement containing the first useful data parameters is transmitted from the second connection controller to the second terminal device after the second connection controller receives an acceptance of the first unidirectional connection by the second terminal device.

4. The method as claimed in claim 1 , further comprising tearing down the preliminary data connection after setting up the second unidirectional connection.

5. The method as claimed in claim 1 , wherein a message is transmitted without the second useful data parameters to the first terminal device during the connection setup signaling and after the second useful data parameters are received at the first connection controller.

6. The method as claimed in claim 1 , wherein third useful data parameters specific to the first terminal device are transmitted from the first terminal device to the second terminal device after the arrival of the second useful data parameters at the first terminal device.

7. The method as claimed in claim 1 , further comprising clearing the established signaling connections of the at least one intermediate controller after setting-up the direct connection between the second connection controller and the first connection controller.

8. A method for setting-up a data connection between a first terminal device connected to a first connection controller and a second terminal device connected to a second connection controller, comprising:

providing a media server that responds to key depressions in, and transmits announcements to, terminal devices;

transmitting a first connection setup message comprising first useful data parameters from the first terminal device to the first connection controller and to the media server, wherein the first useful data parameters comprise address information of the first terminal device;

setting-up a preliminary useful data connection between the media server and the first terminal device, wherein the preliminary useful data connection operates in parallel with setting-up the data connection between the first and second terminal devices;

establishing a signaling connection between the first connection controller and a first intermediate connection controller, and transmitting the first connection setup message from the first connection controller to the first intermediate connection controller using a packet-switched Internet Protocol;

establishing a signaling connection between the first intermediate connection controller and a second intermediate connection controller, and transmitting the first connection setup message from the first intermediate connection controller to the second connection controller using a circuit-switched protocol;

establishing a signaling connection between the second intermediate connection controller and the second connection controller, and transmitting the first connection setup message from the second intermediate connection controller to the second connection controller using the packet-switched Internet Protocol;

storing the first useful data parameters in the second connection controller;

transmitting the first connection setup message without the first useful data parameters from the second connection controller to the second terminal device;

transmitting a connection acknowledgement message comprising second useful data parameters specific to the second terminal device from the second terminal device to the second connection controller;

establishing a direct signaling connection between the second and first connection controllers, and transmitting the acknowledgement message directly from the second to the first connection controller, thence to the first terminal device, bypassing the intermediate connection controllers;

clearing the signaling connections between the second connection controller and the second intermediate connection controller, between the second intermediate connection controller and the first intermediate connection controller, and between the first intermediate connection controller and the first connection controller;

setting-up a first unidirectional useful data connection from the first terminal device to the second terminal device using the direct signaling connection and bypassing the intermediate connection controllers;

transmitting an acceptance message without the second useful data parameters from the second terminal device to the second connection controller;

transmitting the first useful data parameters from the second connection controller to the second terminal device;

setting-up a second unidirectional useful data connection from the second terminal device to the first terminal device using the direct signaling connection and bypassing the intermediate connection controllers;

clearing the preliminary useful data connection; and

performing bi-directional direct communication between the first and second terminal devices using the first and second unidirectional useful data connections.