Access network selection method

An access network selection method in a communications network having multiple access networks, comprising the steps of:

• notifying a device in a calling-side network of an identifier corresponding to a currently available access network and a user preference from a calling-side terminal making a call originating request;
• notifying a device in a called-side network of an identifier corresponding to a currently available access network and a user preference from a called-side terminal having received the call originating request via the device in the calling-side network;
• making a list of candidates for an access network to be assigned to the called-side terminal based on a predetermined condition in response to reception of a notification signal from the called-side terminal as a trigger, and transmitting the list from the device in the called-side network to the device in the calling-side network;
• determining an access network to be assigned to the calling-side terminal in response to reception of the list of the candidates for the access network to be assigned from the device in the called-side network as a trigger, and notifying the calling-side terminal of the determined access network by the device in the calling-side network;
• notifying the device in the called-side network of a type of the access network assigned to the calling-side terminal by one of the calling-side terminal and the device in the calling-side network;
• and
• determining the access network to be assigned to the called-side terminal based on a condition based on which the access network to be assigned to the calling-side terminal has been determined in the device in the calling-side terminal, in response to reception of a signal of the type of the access network assigned to the calling-side terminal as a trigger, and notifying the called-side terminal of the determined access network by the device in the called-side network.