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SIM connectivity troubleshooting guide

This guide walks you through some simple steps to help you troubleshoot your SIM connectivity.

Step 1: Check device configuration​

Please complete the following steps to ensure your devices are configured correctly:

  1. Enable cellular data
  2. Set network preferences to 3G/LTE or 4G/LTE only
    1. Some providers do not allow first time registrations to occur via 2G or 3G connections. Please make sure to complete the initial registration via 3G/LTE or 4G/LTE. After successful initial registration the SIM will be usable via 2G and 2G/3G.
  3. Enable roaming
  4. Set APN as follows (see below for OS specific instructions): 2. Name: Telnyx 3. APN: data00.telnyx 4. Leave all other fields unmodified (even if the fields are blank) 5. Save the new APN.
  5. Enable data roaming on your device
  6. Update your device with the latest firmware
  7. Reboot your device to allow the above changes to take effect

How to configure the APN on Android devices:

  • Navigate to your device settings
  • Select: Mobile Networks → Access Point Names
  • Select the 3 dots icon at the top right and select "Add"

How to configure the APN on iOS devices:

  • Navigate to your device settings by using the gearbox icon.
  • Select: Cellular → Mobile Data → APN

Step 2: View SIM connectivity logs​

You can view your connectivity logs via API or on the portal at: https://portal.telnyx.com/#/app/wireless/sim-cards.

  • Click on the “SIM Card ICCID” field of the SIM in question, on the next page scroll down to the “Connectivity Logs” section.
  • In the Connectivity log table you will see a number of columns. The value in the “Type” column can either be “Registration” or “Data”, this specifies the type of connection the entry represents.
  • The Mobile Country Code (MCC) is a unique 3-digit number to identify a country. It represents the country in which the SIM is connecting.
  • MNC stands for Mobile Network Code. An MNC is a unique 2 – 3 digit code that identifies a mobile network operator (MNO) in a specific country. Each mobile network has a different MNC for each country.
    • Mapping of MCC and MNC codes can be viewed here.

Step 3: Troubleshoot SIM connectivity logs​

Look through the connectivity logs and check for any of the following patterns:

1. No connectivity logs when connecting a SIM​

  • What this means:
    • Your connection attempt isn't reaching Telnyx's core if there are no logs at the time you're trying to connect.
  • Likely reasons:
    • Your SIM might be trying to connect to a network Telnyx can't access.
    • Your device isn’t configured correctly.
    • Your SIM may be in the “deactivated” state, potentially due to reaching a data limit or a payment issue.
  • What to do:
    • Scan for networks to find and select a network that Telnyx supports. This can be done in network settings on most devices. Manually select a network from the list of networks resulting from the scan.
    • Ensure your device is configured correctly; refer to “Step 1: Check device configuration” above for more details.
    • Check your SIM's status in the Telnyx Mission Control portal to see if it's active or has been disabled. When you run out of balance in the portal or reach a data limit your SIMs may move to the disabled state. Add more credit or increase the data limit, then re-attempt connecting.

2. Multiple registration attempts in succession​

  • What this means:
    • If you notice many failed attempts to register in a row without any data being logged, it is likely that your SIM card isn't authenticating with the Telnyx core.
  • Likely reason:
    • Usually, this happens because either:
      1. Data roaming isn't enabled on your device
      2. The APN settings are incorrect. The correct APN is data00.telnyx.
  • What to do:
    • Ensure your device is configured correctly. Please refer to “Step 1: Check device configuration” above for more details.

3. No logs of type “Data”​

  • What this means:
    • If there are no logs of type “Data”, then data sessions are not being created.
  • Likely reason:
    • Similar to above, this usually happens because either:
      1. Data roaming isn't enabled on your device
      2. The APN settings are incorrect. The correct APN is data00.telnyx.
  • What to do:
    • Ensure your device is configured correctly with roaming enabled and the correct APN . Please refer to “Step 1: Check device configuration” above for more details.

If the problem persists, please reach out to our support team who will assist you in investigating further.

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