Open Phone system help you to open the gate by a call. The device has to have installed a SIM card and the line actived.
When you install the device in the garage gate you could open it when you receive a call from authorised telehpone number.
If the call comes from a non-authorised telehpone number, the system doesn´t open the gate. The SIM has to be recharged with a minium of 5€ each 6 months.