The server computer restricts the lifetime of established dial-up connections to 15 minutes from the establishment moment on. Once the connection has been established, if the link is idle for 1 minute, the server computer will also close the established connection to free the telephone line. This control can be implemented through the maxconnect and idle options inside the pppd's configuration file. The server computer allows incoming connections everyday from 10:00PM to 12:00AM. This control can be implemented through a cron job and the /etc/nologin.ttyxx file; where ttyxx represents the device name of your modem (e.g., /etc/nologin.ttyACM0 would prevent the Modem device installed in /dev/ttyACM0 from answering calls).