Overview

Robustel RobustOS routers provide a remote Telnet service that allows users to access the device's operating system and cellular module command line remotely. This feature is particularly useful for scenarios where a Remote Device or PC needs to control the router or send messages via terminal software like SecureCRT without a physical serial connection.

What You'll Need

Before starting the configuration, ensure you have the following hardware and information ready:

Hardware: Robustel RobustOS routers as R2000 or R3000.

• A PC connected to the router via LAN.
• An active SIM card installed in the router.

Software/Firmware: * Router running RobustOS version 2.0.3 or higher.

• Terminal software (e.g., SecureCRT).

Default Credentials: * IP Address: 192.168.0.1

• Username: admin
• Password: admin

Step-by-Step Configuration Guide

Step 1: Configure Link Manager and Cellular WAN

To ensure the router can communicate over the network, you must first establish a primary internet connection.

1. Log in to the Web GUI and navigate to Interface > Link Management.
2. Set the Primary Link to WWAN1 (or the appropriate interface for your SIM card).
3. Navigate to Interface > Link Manager > Link Settings and click Edit for your WWAN interface.
4. Enable Automatic APN Selection or manually enter the APN, Dialup Number (e.g., *99***1#), and credentials provided by your ISP.
5. In Ping Detection Settings, set Enable to ON and provide a Primary Server (e.g., 8.8.8.8) to maintain the connection.
6. Click Submit and then Save & Apply.

Step 2: Enable Remote Telnet Access

By default, remote access services may be restricted for security. You must enable Telnet in the firewall settings.

1. Navigate to Network > Firewall > Filtering.
2. Locate Enable Remote Telnet Access and set it to ON.
3. Locate Enable Local Telnet Access and ensure it is also set to ON.
4. Click Submit and Save & Apply.

Step 3: Configure the Cellular Telnet Port

The AT command interface is mapped to a specific Telnet port.

1. Navigate to Interface > Cellular > Edit.
2. Under General Settings, find the Telnet Port field.
3. Enter a port number (e.g., 7777).
4. Click Submit and Save & Apply.

Verification & Testing

1. Check Network Status

Before testing the terminal, verify that the router has successfully registered on the network.

• Navigate to Status > Internet Status.
• Confirm the Active Link is WWAN1 and an IP Address has been obtained.

2. Connect via SecureCRT

Use your terminal software to establish the connection:

1. Open SecureCRT and start a New Session.
2. Select Protocol as Telnet.
3. Enter the Hostname (Router IP: 192.168.0.1) and the Port you configured (e.g., 7777).
4. Click Connect.

3. Enter AT Commands

Once connected, you can send AT commands to the module. For example, to send an SMS:

1. Type ATE1 and press Enter to enable echo.
2. Type AT+CMGF=1 to set the SMS mode to Text.
3. Type AT+CMGS="[Phone Number]" and press Enter.

4. Type your message (e.g., "hello") and press Ctrl+Z on your keyboard to send.
5. A response of +CMGS: [ID] OK indicates the message was sent successfully.

Troubleshooting / FAQ

• Q1: I cannot connect to the Telnet port (e.g., 2222).
• A: Verify that Remote Telnet Access is enabled in the Firewall settings. Also, ensure your PC's firewall is not blocking the specific port.

• Q2: The AT commands return an "ERROR".
• A: Check if the SIM card is correctly installed and registered to the network. Ensure the router has obtained a valid IP address.

• Q3: Can I use this over a remote cellular IP?
• A: Yes, provided you have a Public Static IP or a VPN connection to the router and Remote Telnet Access is enabled.
  

Conclusion

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