The virtual intercom.

.Using the list in the telephone directory you can give access to visit of your apartment only to familiar people. The virtual intercom will exclude opportunity to ring your door, to uninvited and uninvited guests. Everyone for whom you wait on a visit, call your "door" through the virtual call button installed on your smartphone. It is irreplaceable for owners of private houses. You can customize the list of who to take or not to take "calls on the door," to keep the schedule, configure notifications, and such.
The application has a button SOS. The signal goes to users according to the separate list. When receiving a signal of SOS the system turns on phone in the mode of a siren and when you click on the notification opens a map showing the point where the alarm came. Coordinates with a name sent a signal remain in the separate list.
In the virtual door possible to call, knock and even to shout - these signals will be received by the owner of a door and will be able to answer if necessary.