| 摘要 |
PROBLEM TO BE SOLVED: To limit a range of use of an extension call through a public wireless network to improve convenience of the extension call.SOLUTION: A communication system includes a mobile terminal (3G portable telephone terminal 4) connected by radio to a local area network (enterprise network 8) used for an extension call through a public wireless network (3G portable telephone network 6). A call control part (extension call service server 12) of the mobile terminal periodically and continuously receives registration information of the extension call and sets or updates a valid time of the extension call on the basis of the registration information. The call control part limits within the valid time, an extension line incoming to the mobile terminal through the public wireless network or an extension line call request from the mobile terminal. |
