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+{
+	"title": "ModemManager essentials",
+	"subtitle": "Handling modems from the Linux command line"
+}
+
+#### 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