LTE to GSM switcher

lte-battery-saver.py

import os
import dbus
from gi.repository import GLib
from dbus.mainloop.glib import DBusGMainLoop


best_connectivity="lte"
lowest_connectivity="gsm"
sim_slot="/ril_0"

best_connectivity_cmd=f'/usr/share/ofono/scripts/set-tech-preference {sim_slot} {best_connectivity}'
lowest_connectivity_cmd=f'/usr/share/ofono/scripts/set-tech-preference {sim_slot} {lowest_connectivity}'

def signal_handler(*args, **kwargs):
    [iface, changed, _invalidated] = args
    if 'MobileDataEnabled' in changed:
        mobileDataEnabled = changed['MobileDataEnabled']
        if mobileDataEnabled:
            os.system(best_connectivity_cmd)
        else:
            os.system(lowest_connectivity_cmd)

DBusGMainLoop(set_as_default=True)
bus = dbus.SessionBus()

bus.add_signal_receiver(signal_handler,signal_name='PropertiesChanged',dbus_interface='org.freedesktop.DBus.Properties',
                        path='/com/lomiri/connectivity1/Private'
                        # message_keyword='msg')
                        )

loop = GLib.MainLoop()
loop.run()

lte-battery-saver.service

[Unit]
Description=LTE battery saver
Requires=dbus.socket
After=dbus.socket

[Service]
ExecStart=/home/phablet/.local/bin/lte-battery-saver.sh

[Install]
WantedBy=dbus.socket

from https://forums.ubports.com/topic/6211/howto-alternate-way-of-saving-battery-when-using-4g-lte/70?_=1695711334682
declare systemd service: /home/phablet/.config/systemd/user/lte-battery-saver.service
running the service: systemctl --user enable --now lte-battery-saver

monitor
dbus-monitor --session "type=signal,path='/com/lomiri/connectivity1/Private',interface='org.freedesktop.DBus.Properties',member='PropertiesChanged'"