The Casper or Line Recorder allows one unit to record all phones in the house or office to a single computer. One unit is needed for each phone line. So if there is only one phone number in the home or office only one line recorder will be needed which will be placed next to the computer, if more than one line needs to be recorded multiple recorders can be connected to one computer. Connect the line recorder to the analog lines which come into the phone system if there is a digital phone system in your home or office. For regular phones connect Casper as shown in the link below. Furthermore, the Casper unit will work with wireless phones as well as regular wired phones. USB and phone cables included. Analog phone line required.