With the right modem, IPFire is able to connect to mobile/cellular networks of different types. See a list of compatible modems below.

The modem needs a SIM card which has to be inserted and optionally can be protected by a PIN number.

You can see the status of the modem, as well as the SIM card, if it is registered to the home network or any other network at Status → Modem Status:

All modems emulate a serial interface which is exactly like we have been using since the times of actual serial modems at 56k or less. Therefore we use the same commands to control the modems which are called AT commands.

The number and order of the AT commands can vary from ISP to another one and may also be different for each modem.

To signal to the modem that we are going to need a data connection, we will enter the special phone number *99#.

If the SIM card is PIN-locked, it needs to be unlocked before it can be used. That can be done by sending this AT command as first command to the modem where 1234 is the PIN number:

AT+CPIN="1234"

The APN is required to connect to the correct data network and has to be set with the third AT command:

AT+CGDCONT=1,"IP","internet.t-mobile"

In this example, we use internet.t-mobile as the APN. This has to be changed for other providers and you will get this information from your ISP. A public list of APNs is available here: https://wiki.apnchanger.org

Authentication is necessary for some APNs and the username and password can just be entered into their respective fields.

The method of authentication can either be PAP or CHAP which both are supported by pretty much all ISPs.

• duo optionally comes with a 4G/3G/2G modem by Huawei
  • The modem's serial device is /dev/ttyUSB0 @ 115200 Baud
  • /dev/ttyUSB2 can be used as the monitor device