4G LTE & ModemManager Setup

Once you are booted into Debian or postmarketOS, you need to manage the Qualcomm MDM9625/MDM9207/MSM8916 baseband processor. In modern Linux distributions, this is handled through ModemManager and its command-line companion mmcli.

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1. Verifying Modem Detection

Check if ModemManager recognizes the integrated cellular baseband:

# List detected modems
mmcli -L

Expected output:

/org/freedesktop/ModemManager1/Modem/0 [QUALCOMM] MSM8916

Inspect detailed modem status:

mmcli -m 0

This command outputs manufacturer info, hardware revision, IMEI, SIM status, power state, and supported frequency bands.

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2. Unlocking and Enabling the Radio

Ensure the cellular radio is powered on:

# Enable the modem
mmcli -m 0 -e

If your SIM card has a PIN code:

mmcli -i 0 --pin="1234"

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3. Configuring Carrier APN with NetworkManager

The easiest and most reliable way to maintain persistent cellular connectivity on Linux is using nmcli (NetworkManager):

# Create a cellular connection profile
sudo nmcli connection add \
  type gsm \
  ifname cdc-wdm0 \
  con-name "Cellular-4G" \
  apn "YOUR_CARRIER_APN"

# Example for T-Mobile:
# apn "fast.t-mobile.com"

# Example for Vodafone:
# apn "live.vodafone.com"

# Activate the cellular connection
sudo nmcli connection up "Cellular-4G"

Test your internet connection over 4G:

curl -I https://openstick.org

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4. Reading and Sending SMS via Terminal

Because the modem communicates directly with Linux via QMI/MBIM, you can read incoming verification codes (2FA) and send text messages directly from scripts:

Sending an SMS

# Create SMS object
mmcli -m 0 --messaging-create-sms="text='Hello from OpenStick Linux!',number='+1234567890'"

# Send the created SMS (usually ID 0)
mmcli -s 0 --send

Reading Incoming SMS

# List all messages on the SIM card
mmcli -m 0 --messaging-list-sms

# View message content (e.g. message 0)
mmcli -s 0

This capability forms the foundation of automated SMS verification gateways and Telegram notification bots!