When troubleshooting cellular connectivity issues, the most effective way to check for potential problems is typically to test the device directly. In many cases, running a series of simple tests can help you understand or narrow down what sort of problem is occurring.

In other situations, interacting directly with the modem can also help you understand how it is configured and verify its connection status. This is typically done by accessing the modem's serial interface and sending commands directly to the modem to check how it behaves.

Not all devices will provide access to the modem's serial interface. If you are using a third party device that does not allow you to access the modem's serial interface directly, you may need to check the device's instruction manual for other ways to perform similar troubleshooting steps. Alternatively, you may need to contact the manufacturer for further assistance.

Basic Troubleshooting

In some cases, a connectivity issue may simply be related to the device set up or configuration, such as a loose antenna or a missing setting. Refer to the Basic Connectivity documentation for general tips on how to check if your device is set up correctly.

If you are using a Soracom reference device or starter kit, you can also find dedicated tutorials and guides for how to set up your device:

If you have finished setting up your device but are still having connectivity issues, you can also use the connectivity diagnostics tool to check for basic network problems that might be related to the issue. Refer to the Diagnostics documentation for more information.

Device Troubleshooting

In addition to using the connectivity diagnostics tool to check for basic network problems, you can also perform the following steps to troubleshoot from your device:

Soracom Troubleshooting

If you are using any of the following Soracom features, you can also try temporarily disabling these options as they may affect your device's ability to connect:

Soracom Status Dashboard

In some cases, a connectivity issue may be related to a temporary service issue, such as network maintenance by the local network operator or Soracom platform. In these situations, normal connectivity should be resumed once the issue has been addressed. You can refer to Soracom's Status Dashboard page for known service issues, as well as the local network operator's website for local outage reports.

Advanced Troubleshooting

If you are able to directly access your modem's serial interface, you can use AT commands to check the modem configuration and connection status.

While every modem will have a serial interface, not every device provides a way to access this interface. If you are unsure of whether or not your device allows you to access the modem's serial interface directly, please contact the device manufacturer for more information.

The process for connecting to a modem's serial interface is different for every device. In some cases you may be able to connect directly using a terminal application and, if necessary, an appropriate hardware serial interface adapter. In other cases, you may need to compile a program, prepare a debugging environment, or use custom wiring in order to enable or access the modem's serial interface. The manufacturer of your device can typically provide additional information.

No matter the process for connecting to your modem's serial interface, you will also need to have its AT command manual available. This is typically a PDF file, published by the manufacturer of the modem, and will correspond to the model number of the modem in your device.

While many AT commands are common across all modems, there may be slight variations in the syntax or response. Additionally, newer modems provide additional functionality through the use of extended or vendor-specific AT commands, which will vary from one modem to another.

Make sure to find the AT command manual that corresponds to your modem's manufacturer and model number. You may also want to verify that the AT command manual also corresponds to your modem's firmware version.

Below are the common steps for checking a modem's configuration and connection status.

Modem and SIM Status

Once you are connected to your modem's serial interface, the first step is to check that the modem is responsive:

Next, check that the modem is able to read the SIM:

Finally, make sure the modem is fully enabled:

In addition to the AT+CFUN=1 command to enable full modem functionality, some modems may have advanced features such as Power Saving Mode (PSM) which may automatically disable the modem at specific intervals in order to reduce power consumption. When troubleshooting, you may want to temporarily disable these features as they may interfere with your ability to interact with the modem.

Radio Technology and Frequency Band

Make sure that the radio technology you are trying to use (such as 2G, 3G, 4G/LTE, or LTE-M) is enabled. This is especially true for Cat-M1/NB-IoT modems, where one of the radio technologies may be disabled by default, depending on what radio technologies are typically available in your region.

Similarly, you may want to check if the corresponding frequency bands used by the local network operator are also enabled in the modem.

The AT commands for enabling radio technologies and frequency bands are typically different for each modem manufacturer and model. Refer to your AT command manual for specific instructions.

Operator Selection

Next is to select a local network operator that the modem will connect to. Typically, this is done by first performing a network search:

Once the network search has finished, most modems will automatically select one of the available networks. You can check which network operator the modem has selected:

If the modem was able to find one or more available network operators but did not automatically select one, or if you prefer to override the automatic selection in order to connect to a different network operator, you can manually select a network operator instead:

You will want to verify that the manual network operator selection was effective by using the AT+COPS? command described above.

If you manually selected a network operator but want to revert to automatic selection, you can do so using AT+COPS=0.

Your AT command manual will have more information on how to read the list of available network operators response from the modem, as well as additional options for manually selecting a network operator.

For more information on what network operators you can use with your Soracom SIM, refer to the Supported Carriers documentation.

Network Registration

Once a network operator has been selected (either automatically by the modem or manually by custom input), the modem should attempt to register to the network. To confirm that the modem is registered to the selected network operator:

At this stage, if your SIM status is Ready or Standby, Soracom will automatically activate or reactivate your SIM and change its status to Active. You should be able to see this change in the User Console.

Signal Quality

Although a modem may be registered to a network, the signal quality may affect its ability to reliably send or receive data. To check the signal quality:

Refer to your modem's AT command manual for more information on what values are acceptable.

Newer modems also provide additional AT commands for checking additional signal strength values.

If the signal quality appears to be too low, try reorienting your modem's antenna or moving your device to a new location, and repeating the command, until you have found a suitable location that provides good signal quality.

PDP Context Configuration

With the modem successfully registered to a network operator and within an area with good signal quality, the next step is to establish a data connection. This is done by configuring a Packet Data Protocol (PDP) Context, where you specify Soracom's Access Point Name (APN):

Then to check that your PDP Context configuration is stored correctly:

Some modems may have additional AT commands for configuring username and password authentication. As Soracom verifies cellular connectivity based on SIM authentication, there is generally no need to manually configure additional authentication settings. However, if your modem's AT command manual recommends configuring username and password authentication, you can use the following parameters:

  • Username - sora
  • Password - sora
  • Authentication Type - PAP, CHAP, or Automatic

PDP Context Activation

Next, the modem will check which 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.

When creating a PDP Context, most modems will automatically activate the PDP Context at the same time. To check that the PDP Context is activated:

If the PDP Context containing the Soracom APN is not activated, you can activate it using:

Once you have activated a PDP Context profile, you can repeat the AT+CGACT? command to check the activation status.

Packet Domain Attachment

Finally, with a PDP Context configured and activated, the modem is now ready to create a data session. This is done by attaching to the network operator's packet domain service.

Similar to PDP Context activation, most modems will automatically attach to the packet domain at the same time. To check that the modem has attached:

If the modem is not attached to the network operator's packet domain, you can attach it using:

Once the modem has attached to the packet domain, you can repeat the AT+CGATT? command to check the attach status.

At this point, your SIM should appear as Online in the User Console.

Additional Commands

You can also perform some additional AT commands to further confirm that your modem has successfully connected to a network and established a data connection.

If your device supports 2G or 3G connectivity:

If your device supports LTE connectivity (including LTE-M):

Last, you can also verify that your modem has received an IP address from Soracom, indicating that IP connectivity was successfully set up: