4-8 IBM Personal Computer User GuideSetting up communicationsIf your computer has a fax/data modem, it can communicate with other computersand fax machines.Some IBM personal computers have a modem already installed. However, if yourcomputer package comes with a modem but it is not installed, open the system andinstall the modem first. Refer to sections ”Opening the system unit” on page 7-5 and”Adding and removing adapter cards” on page 8-4 for instructions.Before your computer can use its modem, you must complete the procedures in thefollowing sections:• Connecting your modem to the telephone network• Configuring your communications softwareConnecting your modem to the telephone networkModems are designed to operate over thepublic switched telephone network(PSTN or PSN). This is ananalog network commonly used by most households.Connect the modem to an analog networkonly. If you are not sure about yourtelephone line, contact your local telephone company.Before you connect your modem to a telephone network, read the safety notices in“Safety information” on page xi.Attention!• Excessive voltages can occur on telephonelines, especially during lightning storms. Toavoid any possible damage to sensitiveelectronic parts, unplug the computer and thetelephone cords during such storms.• Some businesses, schools, and buildings havedigital telephone systems, known as digitalprivate branch exchange (PBX) systems. Thesesystems do not work with the modem.Connecting your modem to a digital telephonesystem might damage the modem.
