Mobile communication terminal apparatus, method for controlling mobile communication terminal apparatus, and communication system

A method for controlling a mobile communication terminal apparatus, the method comprising:

• determining whether to have received first notification information when receiving an instruction to switch to communication using a second communication network in a state of connecting to a first communication network from which the first notification information and second notification information being additional information of the first notification information are received;
• executing switching of a connection from the first communication network to the second communication network and communicating by use of the second communication network when not having received the first notification information;
• and
• continuing wait for receipt of the second notification information without switching connections from the first communication network to the second communication network when having received the first notification information and not having received the second notification information.

A communication system comprising:

• a first communication system;
• a second communication system;
• and
• a mobile communication terminal apparatus, wherein
• the first communication system includes a notification information transmission apparatus that transmits to the mobile communication terminal apparatus first notification information and second notification information being additional information of the first notification information, by use of a first communication network,
• the second communication system includes a communication apparatus that communicates with the mobile communication terminal apparatus by use of a second communication network,
• the mobile communication terminal apparatus includes
• a first communication unit that receives the first notification information and the second notification information, which are transmitted from the notification information transmission apparatus by use of the first communication network,
• a second communication unit that communicates with the communication apparatus by use of the second communication network,
• a switching control unit that receives an instruction to switch to communication using the second communication network when connecting to the first communication network, switches connections from the first communication network to the second communication network when the first communication unit has not received the first notification information, and holds switching of a connection from the first communication network to the second communication network when the first communication unit has received the first notification information and has not received the second notification information.