{
	"title": "modemmanager",
	"subtitle": "Handling modems from the Linux command line",
	"aliases": [
		"/articles/modemmanager-essentials"
	]
}

#### Introduction

The software [ModemManager][4] handles modems on Linux operating systems. It
has the `mmcli` command line utility included which exposes its functionality.

It is possible to use `mmcli` to setup mobile internet connections, make phone
calls and send SMS.

This article summarizes some basic `mmcli` commands. It was written to further
debug the issue described in [this postmarketOS issue][5].

#### Get modem summary

With this command a summary about the modem is printed. It assumes just one
connected modem (`-m any`) which should be given on nearly all devices:

```
mmcli -m any
```

#### Unlock a SIM card

To actually do something with the modem it might be necessary to unlock the
inserted SIM card:

```
# this command needs appropriate polkit authentication or root permissions
mmcli -i "/org/freedesktop/ModemManager1/SIM/0" --pin "1234"
```

Use the SIM path listed in the summary (see section above).

#### Enable modem

In addition to unlocking the SIM card it is required to enable the modem:

```
# this command needs appropriate polkit authentication or root permissions
mmcli -m any -e
```

#### List calls

This command lists active, ringing, terminated and other calls:

```
mmcli -m any --voice-list-calls
```

The idea is that calls are tracked with the identifiers printed by this command
which allows to send additional commands like accept or hangup.

#### Accept a call

An incoming call can be accepted like this:

```
# this command needs appropriate polkit authentication or root permissions
mmcli -m any -o "/org/freedesktop/ModemManager1/Call/0" --accept
```

#### Hangup a call

Any active call can be hung up like this:

```
# this command needs appropriate polkit authentication or root permissions
mmcli -m any -o "/org/freedesktop/ModemManager1/Call/0" --hangup
```

#### Create a call

To create a call one can use the following command. Take care to select the
right phone number format. Given is an example phone number with German
international prefix `+49`.

```
mmcli -m any --voice-create-call "number=+49123456789"
```

This command just registeres a new call. To actually start it one has to get
its identifier with listing all calls and then start it like this:

```
# this command needs appropriate polkit authentication or root permissions
mmcli -m any -o "/org/freedesktop/ModemManager1/Call/4" --start
```

It can be hung up like incoming calls.

#### Further documentation

Running `mmcli --help` and the there listed help commands provide a summary of
all the functionality ModemManager provides. This article is just a brief
subset of it.

The [SXMO modem scripts][1] from the [SXMO project][2] helped me a lot to write
this summary aswell as the [Chromium mmcli help page][3].

Of course the [ModemManager homepage][4] is the most official entry point to
search for further documentation.

[1]: https://git.sr.ht/~mil/sxmo-utils/tree/master/item/scripts/modem
[2]: https://sxmo.org/
[3]: https://www.chromium.org/chromium-os/how-tos-and-troubleshooting/debugging-3g/modem-debugging-with-mmcli/
[4]: https://www.freedesktop.org/wiki/Software/ModemManager/
[5]: https://gitlab.com/postmarketOS/pmaports/-/issues/2113