This application works as a keyring and can send SMS with password to the Gate app to open the gate.
Use this app together with "Open Sesame Gate" https://play.google.com/store/apps/details?id=com.fletech.android.opensesame.gate
After installation add a key: set the password, and the phone number of your friend who has the Gate app. Now you can click on the key to send an SMS to your friend, and the Gate app will automatically open the gate.