Most of the houses, apartments, offices today are equipped with one or another warning device, which allows civilized enough to announce his arrival and wish to join. Quite often this is the usual cheesy, but effective electromechanical bell or buzzer. In fact, experiments with the signal fed by electricity carried in the eighteenth century. But it took time to get out of the field experiment, these devices are switched to the practical application in everyday life. Therefore, in the not too distant past, even the door bell was a novelty, the capital of fun, not to mention the modern electric bell. Remember a classic announcement on the door: "Prozba derbanit not in the front door, and a finger in your navel Suva to call!".
Of mallets, gongs, bells ordinary household relay alarms transmitted to the electro-calls, calls electronics and a solid set of sounds and melodies, and then to wireless calls. It should be noted that the newest electronic wireless calls is very convenient because you can have more than one call button and more than one speaker, as well as not to mess with wires. Yes, and power the electrical devices can be not only on the 220V transformer, and batteries that are much safer. Another undoubted advantage of modern phone calls for many is a huge variety of shapes, sizes, colors, buttons and speakers. After all, few people already like a dull gray spot above the door – the device should be hidden or be part of the design hall, organically fit into the interior as if it were an office computer desk in the corner. But if, despite all the "steepness" of the latest devices, given your sympathies "real" bell, then, except for the signal and decorative features, it can be a talisman, as it can be applied even though the Celtic runes, though the Chinese characters, although traditional Russian wishes of good luck and a guest house.