Patent ID: 8711845

Claim:
A communication terminal device comprising: a first communication unit performing data communication in a first communication mode specializing in packet communication via a first communication system; a second communication unit performing data communication in a second communication mode supporting voice communication via a second communication system; an instruction input unit receiving input of a voice communication start instruction; and a control unit controlling said first communication unit and said second communication unit, wherein: said control unit controls said first communication unit to perform data communication via said first communication system until said instruction input unit receives said input of a voice communication start instruction, when said instruction input unit receives said input of the voice communication start instruction, requests said second communication system to send access control information indicating a total or a partial restriction of an access between said communication terminal device and said second communication system, receives said access control information sent from said second communication system in response to said request, and determines not to perform data communication via said second communication system if said received access control information indicates a total restriction or a restriction of equal to or greater than a predetermined level on the access between said communication terminal device and said second communication system, and determines to perform the data communication via said second communication system if said received access control information indicates a restriction of less than the predetermined level, and prevents said second communication unit from performing data communication if said control unit determines not to perform data communication via said second communication system, and controls said first communication unit to request said first communication system to execute a suspension procedure and controls said second communication unit to perform voice communication via said second communication system if said control until determines to perform data communication via said second communication system.