Internet telephony system

An internet telephony system comprising:

• a plurality of switching equipment which accommodate a plurality of terminals which can perform at least one of voice communication and data communication;
• an internet network including a gate keeper;
• and
• a plurality of gateways which connect the plurality of switching equipment to the internet network, make it possible to perform communication through the switching equipment and the internet network by communication protocol conversion, and accommodate a terminal which can perform at least one of voice communication and data communication,
• wherein, in a call transfer operation in which transition from a communication state between a first terminal accommodated with a first switching equipment of the plurality of switching equipment and a second terminal accommodated with a second switching equipment of the plurality of switching equipment to a communication state between a third terminal accommodated with a first gateway of the plurality of gateways, corresponding to the second switching equipment, and the second terminal is performed,
• the gate keeper checks whether path replacement for setting the call transfer operation is required or not, and adds information for the path replacement to an information element of a message regulated by a specific communication protocol related to the call transfer operation, when the path replacement is required, to notify the second switching equipment on a path replacement side of the information through the first gateway,
• the first gateway checks whether the path replacement for setting the call transfer operation is required or not based on the information notified by the gate keeper, and notifies the second switching equipment on the path replacement side of the information when the path replacement is required, and
• communication between the second terminal and the third terminal after the call transfer operation is provided by a path managed by the second switching equipment and a path managed by the first gateway, and the paths obtained after the call transfer operation are not through a circuit of the internet network.

An internet telephony system comprising:

• a plurality of switching equipment which accommodate a plurality of terminals which can perform at least one of voice communication and data communication;
• an internet network including a gate keeper;
• and
• a plurality of gateways which connect the plurality of switching equipment to the internet network and make it possible to perform communication through the switching equipment and the internet network by communication protocol conversion,
• wherein, in a call transfer operation in which transition from a communication state between a first terminal accommodated with a first switching equipment of the plurality of switching equipment and a second terminal accommodated with a second switching equipment of the plurality of switching equipment to a communication state between a third terminal accommodated with a third switching equipment connected to a first gateway of the plurality of gateways, corresponding to the second switching equipment, and the second terminal is performed,
• the gate keeper checks whether path replacement for setting the call transfer operation is required or not, and adds information for the path replacement to an information element of a message regulated by a specific communication protocol related to the call transfer operation, when the path replacement is required, to notify the second and third switching equipment on a path replacement side of the information through the first gateway,
• the first gateway checks whether the path replacement for setting the call transfer operation is required or not based on the information notified by the gate keeper, and notifies the second and third switching equipment on the path replacement side of the information when the path replacement is required, and
• communication between the second terminal and the third terminal after the call transfer operation is provided by paths respectively managed by the second switching equipment and the third switching equipment and a path managed by the first gateway, and all of the paths obtained after the call transfer operation are not through a circuit of the internet network.

A gateway comprising:

• means for checking whether path replacement for setting a call transfer operation is required or not;
• based on information for the path replacement in an information element of a message regulated by a specific communication protocol related to the call transfer operation;
• and
• means for notifying a second switching equipment on a path replacement side of the information through self-gateway when the path replacement is required;
• wherein, in the call transfer operation in which transition from a communication state, through an internet network, between a first terminal accommodated with a first switching equipment and a second terminal accommodated with the second switching equipment to a communication state between a third terminal accommodated with the second switching equipment and the second terminal is performed,
• communication between the second terminal and the third terminal after the call transfer operation is provided by a path merely managed by the second switching equipment, and the path obtained after the call transfer operation is not through a circuit of the internet network.

A gateway comprising:

• means for checking whether path replacement for setting a call transfer operation is required or not based on information for the path replacement in an information element of a message regulated by a specific communication protocol related to the call transfer operation;
• and
• means for notifying a second switching equipment on a path replacement side of the information through self-gateway when the path replacement is required;
• wherein, in the call transfer operation in which transition from a communication state, through an internet network, between a first terminal accommodated with a first switching equipment and a second terminal accommodated with the second switching equipment to a communication state between a third terminal accommodated with the self-gateway, corresponding to the second switching equipment, and the second terminal is performed,
• communication between the second terminal and the third terminal after the call transfer operation is provided by a path managed by the second switching equipment and a path managed by the self-gateway, and the paths obtained after the call transfer operation are not through a circuit of the internet network.

A gateway comprising:

• means for checking whether path replacement for setting a call transfer operation is required or not based on information for the path replacement in an information element of a message regulated by a specific communication protocol related to the call transfer operation;
• and
• means for notifying a second switching equipment and a third switching equipment on a path replacement side of the information through self-gateway when the path replacement is required;
• wherein, in the call transfer operation in which transition from a communication state, through an internet network, between a first terminal accommodated with a first switching equipment and a second terminal accommodated with the second switching equipment to a communication state between a third terminal accommodated with the third switching equipment connected to the self-gateway, corresponding to the second switching equipment, and the second terminal is performed,
• communication between the second terminal and the third terminal after the call transfer operation is provided by paths respectively managed by the second switching equipment and the third switching equipment and a path managed by the self-gateway, and all of the paths obtained after the call transfer operation are not through a circuit of the internet network.