Logging in through a pair of modems

You can use a pair of modems to remotely connect to the console port of the device over PSTN when no IP network connection is available.

By default, modem dial-in is enabled and does not require authentication. To improve device security, configure password or scheme authentication for the AUX line immediately after you log in to the device for the first time. The configuration procedure is the same as described in "Configuring local console login."

Before using a pair of modems to log in to the device, you must prepare a console terminal, for example, a PC. Make sure the console terminal has a terminal emulation program, such as HyperTerminal or PuTTY. For information about how to use terminal emulation programs, see the programs' user guides.

To use a pair of modems to log in to the device:

1. Connect one modem to the serial port of the PC and another modem to the console port of the device.

2. Connect each modem to the PSTN through a telephone cable.

3. Obtain the telephone number of the device-side modem.

4. Configure the following settings on the device-side modem:

   • AT&F—Restores the factory default.

   • ATS0=1—Configures auto-answer on first ring.

   • AT&D—Ignores DTR signals.

   • AT&K0—Disables local flow control.

   • AT&R1—Ignores RTS signals.

   • AT&S0—Forces DSR to remain on.

   • ATEQ1&W—Disables the modem from returning command responses and execution results, and saves configuration.

   To verify your configuration, enter AT&V to display the configuration results.

   	NOTE: The configuration commands and output vary by modem model. For more information, see the modem user guide.

5. To ensure successful communication and to avoid data loss, verify that the console port uses the following settings:

   • The default parity, stop bits, and data bits settings.

   • A baud rate that is lower than the transmission rate of the modem.

   In AUX line view, you can also manage modem dial-in users. For more information, see Layer 2–WAN Access Configuration Guide.

6. Launch the terminal emulation program on the PC and create a connection using the telephone number of the device-side modem.

7. Dial the telephone number to establish a connection to the device.

8. After you hear the dial tone, press Enter as prompted.

   If the authentication mode is none, the prompt <HPE> appears. If the authentication mode is password or scheme, you must enter the correct authentication information.

   	IMPORTANT: Do not directly close the HyperTerminal. Doing so can cause some modems to stay in use, and all subsequent dial-in attempts will fail.

To terminate the modem connection to the device, execute the ATH command in the HyperTerminal. If the command cannot be entered, enter AT+ + +. When the word OK appears, execute the ATH command. The connection is terminated if OK is displayed. You can also terminate the connection by clicking in the HyperTerminal window.