• CELL
  • Intermediate
  • 3 min
  • Serial CLI

Recipe · Intermediate · CELL

How to check a cellular modem in CELL mode

Cellular failures are often power, antenna, SIM or registration problems. The CELL mode gives you a structured status check before using higher-level operations.

Cellular modem with SIM card and radio signal.
Query modem, SIM and network state in a safe diagnostic order.

Wiring View

Modem BP TXBP RXRXBP TXGNDBP GNDPWRproper modem su...
Generated from the wiring summary: Modem to BP.
Step 1

Commands

Run the commands below after selecting the right Bit Pirate mode and confirming the wiring.

Result

What success looks like

You can distinguish a wiring/power issue from a SIM or network registration issue. If the modem command fails, fix UART/power before anything else.

Troubleshooting

  • Modem supply cannot provide burst current.
  • Antenna missing.
  • SIM locked or absent.
  • RX/TX swapped or wrong UART settings.

Next steps

  • Use unlock only for your own SIM if PIN is required.
  • Use sms or ussd only after registration is confirmed.
  • Log modem and network output before debugging the application layer.

cellular modem status FAQ

What does modem status prove?

It proves that the UART path to the modem is alive and that basic modem information can be queried. It is the foundation for SIM, operator and network-registration checks.

What is the difference between modem, SIM and network checks?

Modem checks prove AT communication, SIM checks prove subscriber-card state, and network checks prove registration with an operator. Each layer can pass or fail independently.

Which command should I run first when debugging CELL mode?

Start with modem because it proves the AT interface and module firmware respond. Then check sim, network and operator before using SMS, calls or USSD.

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