Quectel EG25 GSM modem to SIP Call Gateway Bot

GSM call forwarding to SIP. A bot that forwards calls (or SMS) from a Quectel EG25 LTE modem to a SIP URI

Required setup:

• A Quectel EG25-G based modem. For example, EG25-G USB modem from Aliexpress (Separate IPX antenna required)
  • This is the same modem module that is used on the PinePhone (https://www.pine64.org/pinephone/) and in the Librem 5 design (https://puri.sm/products/librem-5/)
  • This project uses an open source custom firmware for the modem: https://github.com/Biktorgj/pinephone_modem_sdk/ (With the EN_USBAUD feature enabled)

Prerequisites

This uses docker, and also assumes a proper setup of the hardware on the host environment. Essentially, the following udev rules should be placed (for examle) into /etc/udev/rules.d/89-lte-modem.rules on the host machine:

ATTRS{idVendor}=="2c7c", ATTRS{idProduct}=="0125", ENV{PULSE_IGNORE}="1"
DRIVERS=="usb", KERNEL=="*cdc-wdm*", GROUP="dialout"

The Vendor and Product IDs here match the Quectel modem. This is necessary for the USB sound-card exposed by the modem to the host to be available for this software, and for permissions to be matching (dialout group, precisely). Running cat /proc/asound/cards should show something like the following with regards to the Quectel modem soundcard:

$ cat /proc/asound/cards
...
 2 [Module         ]: USB-Audio - LTE Module
                      Quectel, Incorporated LTE Module at usb-0000:00:14.0-4.1, high speed

The name of the soundcard is Module. Apart from this, the AT command port of the modem should be found, on a path like /dev/ttyUSB2, and the QMI port under /dev/cdc-wdm0. Both need to be usable by the dialout group on your host.

Building and running

./doit.sh --sip_dest <SIP-URI> --modem_tty /dev/ttyUSB2 --modem_dev /dev/cdc-wdm0

This builds the docker image, and runs it as daemon that also survives reboots. The ouput can be seen using docker logs -f gsm-sip-gw-container

Modem setup

The modem needs to be configured with some AT commands before use. Depending on what you need, refer to at.txt in this repo.

eSIM (eUICC) support

You can attach a Consumer eUICC (for example, the esim.me card) to the Quectel modem. In order to manage the eSIMs, run:

./apdu.py --modem_tty /dev/ttyUSB2

And then run the forked LPAdesktop build from here: https://github.com/gregvish/LPAdesktop/releases/tag/v1.0 That will connect to the apdu.py and provide a GUI for managing eSIM sims.