For making PSTN calls you must have an already activated telephone service from a service provider. Connect the “LINE” cable of the Splitter provided with the modem, to telephone/internet socket in your home, connect a telephone instrument to the “PHONE” port of the splitter using a telephone cable (RJ11) and connect the modem to the “MODEM” port of the splitter. For more information, refer the connection diagram shown on the user guide provided with the modem or contact our Technical support team. You should be able to make and receive the PSTN calls using the telephone instrument connected to the “PHONE” port of Splitter.