A push could be a device generally placed close to a door to a building's entrance. once a traveller presses a button the bell rings within the building, alerting the resident to the presence of the traveller. though the primary doorbells were mechanical, activated by pull a twine, trendy doorbells are electrical, operated by a push button switch. trendy doorbells typically incorporate intercoms and miniature video cameras to extend security. Doorbell Types Traditional doorbell Wireless doorbell Intercom doorbell ...