The modem device installation consists on attacthing the modem hardware both to the computer and the telephone line. To connect the modem to your computer, you need to connect the serial or USB cable that comes from the modem hardware to the appropriate input on your computer. To connect the modem to the telephone line system, you need to unplug the cable that connects your phone device and plug it on the modem device, specifically in the port reserved for data transmission. Later, using a similar cable, you could connect your phone device to the modem's phone port, so you be able of realizing phone calls when no data transmition take place, as well. To be on the safe side, do all the installation with the computer turned off. Then, when everthing has been put in place, turn it on. Once the system is up, you can verify the modem hardware using either the lsusb or lspci commands. For example, if you are using an USB modem like that one we mentioned before, run the following command: sudo /sbin/lsusb and you should get an output similar to the following: Bus 003 Device 001: ID 0000:0000 Bus 001 Device 001: ID 0000:0000 Bus 001 Device 002: ID 058f:6366 Alcor Micro Corp. Multi Flash Reader Bus 002 Device 001: ID 0000:0000 Bus 005 Device 003: ID 06e0:f104 Multi-Tech Systems, Inc. MT5634ZBA-USB MultiModemUSB (new firmware) Bus 005 Device 001: ID 0000:0000 Bus 005 Device 002: ID 046d:c018 Logitech, Inc. Optical Wheel Mouse Bus 004 Device 001: ID 0000:0000 The relevant line here is that mentioning the existence of a Multi-Tech System, Inc. MT5634ZBA-USB MultiModemUSB (new firmware) device. At this point, your computer should be able of responding to incoming calls but cannot realize outgoing calls, yet. To administer the way incoming calls are attended in this computer, read . On the other hand, to realize outgoing calls from this computer, you need to specify the server information you want to establish connection to, as described in .