Is It Recommended to Configure Modems Manually?

Manual configuration of modems is often necessary for initial device setup, troubleshooting connectivity issues, and verifying modem behavior in the field. Depending on your hardware, this configuration might be handled automatically by your operating system, through a user interface, or manually using AT commands.

While Soracom IoT SIMs handle authentication automatically if the network allows it, you typically need to configure the Access Point Name (APN) and may need to adjust radio settings to establish a connection.

General Device and SIM Configuration

Before configuring your software, ensure your Soracom IoT SIM card is inserted into the device's SIM slot following the correct orientation. Take care to avoid using unnecessary force, which could cause permanent damage and render the SIM card unusable.

The process for configuring your device depends heavily on your hardware:

• UI and Apps: Some devices allow you to enter configuration settings through a web admin UI or a built-in application.
• Connection Managers (Linux): For USB modems (such as the Soracom Onyx LTE USB Modem) connected to Linux devices like Raspberry Pi or NVIDIA Jetson, it is highly recommended to use NetworkManager. NetworkManager fully manages the modem and enables automatic internet connections without manual dialing. If NetworkManager is unavailable (such as on certain embedded gateways or routers), WvDial is a reliable alternative.
• Manual Configuration: Other devices may require direct configuration using SMS or AT commands.

Configuring Access Credentials and APN

When a device or modem connects to a cellular network, the Access Point Name (APN) is used by the network to establish data connectivity. You must set up the APN on your device so the local network operator can correctly route your data connection to Soracom.

Next, the modem will check which Packet Data Protocol (PDP) Context it should use in order to establish a data connection. This can be controlled by activating (or deactivating) a PDP Context, using its PDP Context profile number.

If your device requires you to manually configure access credentials, use the following standard settings (note that some devices may not require all of these):

• Access Point Name (APN): soracom.io
• Username: sora
• Password: sora
• Authentication Type: PAP, CHAP, or Automatic
• PDP Type: IP or IPv4

Note: Because Soracom verifies cellular connectivity based on SIM authentication, there is generally no need to manually configure the username and password settings. However, you should provide them if your modem's manual explicitly recommends configuring authentication.

Accessing the AT Command Interface

AT commands are text-based instructions sent to a modem over a serial interface. The name comes from the word "attention"—each command begins with the prefix AT to signal the modem that an instruction follows. While standardized by 3GPP and ETSI, manufacturers often provide additional vendor-specific commands.

To send AT commands, you need a serial or USB connection between your computer (or terminal) and the modem. The typical setup involves:

1. Connecting your computer to the modem's serial or USB interface using an appropriate cable or adapter.
2. Opening a serial terminal application and connecting to the correct port at the modem's configured baud rate.

Common serial terminal applications include:

• Windows: PuTTY or Tera Term, connected to the COM port where the modem is attached.
• macOS / Linux: The screen or minicom command, connected to a device file such as /dev/tty.usbmodem* or /dev/ttyUSB*. For example: screen /dev/ttyUSB0 115200 or minicom -D /dev/ttyUSB0 -b 115200.

Some devices also provide access to the AT command interface through a built-in console, web interface, or debug port. Check your device's documentation for details.

Important: Not all devices expose the modem's serial interface. If you are unsure whether your device allows direct access, review the device manual or contact the device manufacturer. Soracom does not provide a way to send AT commands to a modem that does not natively support them. While Soracom offers remote access services, these only work if the device itself natively supports and has been configured for remote access to its AT command interface.

Common AT Command Configuration Tasks

When working with cellular IoT devices, you may need to interact directly with the modem to verify that the modem detects the SIM, check network registration, view or change the selected network operator, or enable/disable modem functionality. Common tasks include:

• Checking Modem Status: Once connected to the serial interface, you can send the ATI command to verify that the modem is responsive.
• Verifying SIM Detection: Send AT+CPIN?, which should return READY. To confirm the modem sees the SIM you expect, use AT+CCID (or AT+ICCID, depending on the module) to read the ICCID and compare it against the SIM in the Soracom User Console.
• Enabling Radio Technologies and Bands: Make sure the radio technology you are trying to use (2G, 3G, 4G/LTE, or LTE-M) is enabled. For some devices (especially Cat-M1/NB-IoT), specific radio technologies or frequency bands may be disabled by default depending on your region and must be manually enabled. Take the modem offline with AT+CFUN=0, apply the change, then re-enable it with AT+CFUN=1. The exact command is module-specific — for example, AT%XSYSTEMMODE=1,0,0,0 (Nordic nRF91, LTE-M only), AT+URAT=7 (u-blox SARA-R4/R5, LTE-M), or AT+QCFG="iotopmode",0,1 (Quectel BG9x, LTE-M). Bands are typically configured with a bitmask, such as AT%XBANDLOCK, AT+UBANDMASK=0,<mask>, or AT+QCFG="band",.... Once configured, AT+COPS=? triggers a network scan so you can confirm the modem sees operators on the enabled bands.
• Checking Signal Quality: Use AT+CSQ for a quick RSSI reading, or AT+CESQ for the extended report, which includes RSRP and RSRQ — the values that matter most for LTE-M and NB-IoT link quality. Many vendors also offer richer variants, such as AT+QCSQ on Quectel or AT%CESQ on Nordic. If the signal appears too low, try reorienting your modem's antenna or moving your device to a new location until you find a suitable spot.
• Checking Network Registration: Use AT+CEREG? for LTE-M and NB-IoT, or AT+CREG? / AT+CGREG? on 2G and 3G. Sending AT+CEREG=2 beforehand includes the cell ID and TAC in the response, which is useful when correlating device behavior against session logs in the Soracom User Console.
• Configuring the APN (PDP Context): You must specify Soracom's APN in the PDP Context configuration to establish a data connection. For example, you can set the APN using the command AT+CGDCONT=1,"IP","soracom.io".
• Enabling and Disabling the Modem: Use AT+CFUN=1 for full functionality, AT+CFUN=0 to power down the radio, and AT+CFUN=4 for airplane mode (radio off, SIM still accessible).

Safety Considerations

While manual configuration is often required, you should proceed with caution. Incorrect parameters can leave the modem in a state that requires a factory reset to recover. If you are unsure about a command or its parameters, consult the manual or contact the modem manufacturer before proceeding.

Before sending commands, consider the following:

• Consult the Manual: Always have the AT command manual available that corresponds exactly to your modem's manufacturer, model number, and firmware version. While many AT commands are common, syntax and responses can vary, and newer modems often use extended or vendor-specific commands.
• Persistent Settings: Some commands change modem settings that survive a reboot. Incorrect values can affect the modem's ability to connect until they are corrected.
• Connection Loss: Commands that disable the modem's radio (such as AT+CFUN=0) will immediately drop any active connection. If you are connected to the device remotely, this can make it unreachable.
• Network Disruption: Changing the APN, authentication, or operator selection to incorrect values can prevent the modem from reconnecting to the network.
• Read Before Write: Use the read form (AT+CMD?) before using the write form (AT+CMD=<value>) so you understand the current configuration before changing it.

For more details on standard commands and safety, refer to the AT Commands documentation. If you are using transferred SIMs and they require specific configuration for existing devices, reach out to the owner of the source Soracom account for the appropriate settings.