Use this app if you live in a place where there's a gate that needs to be opened by calling a phone number from your phone.
After installation set a password, and the phone number of the gate.
Tell the password to your friends or invite them to the "Open Sesame Key" app: https://play.google.com/store/apps/details?id=com.fletech.android.opensesame.key
Now they can send you an SMS with the password and the phone number of the gate will be called automatically.