This manual describes two computers configuration, one acting as server and other as client. The server computer will be configured to provide internet services and the client to make use of those internet services provided by the server computer. The connection medium both client and server computer use is the telelphone line (i.e., the same medium you use to realize phone calls). In this configuration, both client and server computers use special devices named Modems to transmit data in form of sound across the telephone line. The infrastructure described in this chapter is made available to you free of charge, however, you should know that maintaining it costs both money and time. For example, for each hour the server computer is on production there is an electrical consume that need to be paid every month. Likewise, each call that you establish from the client computer to the server computer will cost you money, based on the location you made the call from and the time you spend connected. The infrastructure described in this chapter could be a good choise when the only communication medium you have access to is a telephone network.