To control the working status of a modem, configure the device to send AT commands to the modem according to the AT command set supported by the modem.

Many manufacturers produce different types of modems. These modems support the standard AT command set but differ in implementations and configuration commands. To enable the device to communicate with devices over a PSTN through a modem, you can configure the device to send AT commands to the modem according to the AT command set supported by the modem.

Incorrect configuration may cause incorrect modem status, affecting the dialing function. Therefore, exercise caution when using AT commands to configure a modem.