How do you know when they sound if you‘re inside of a building? How long before they stop?
Well it all depends on the year and make of the car. If the car was purchased in 2008-2009 it may call or send you a text message, but that is only if you have a VERY expensive luxury car. Some cars turn off in a few minutes, and other can go on and on until you turn it off.
There are many types of car alarms. They have been around for a very long time. The first ones were just some type of balance beam inside a box that you would wire to your car horn. When someone got in the car, or bumped it hard enough the contacts on the balance beam would connect to voltage to honk the horn. This type was just an instant horn honk, and would stop when the car was no longer being tipped, bumped, moved, or anything else that would make that contact arm move. Today, we have on-board alarms, add-on alarms, simple electronic (instead of the old mechanical such as mentioned above), and very complex electronic that can even be programmed for whatever type of alarm alert you may want. The simple electronic alarm is one that is designed to set off a signal to alert anyone around that it has gone off, but will only sound for a few seconds, to a few minutes. All electronic alarms can be programmed to give that audible alarm for as long a time as a person desires. Some can be set by the car owner, while others must be set by some shop. More complex alarm systems can send out radio signals to a phone, the police department, a monitoring station, and even to use GPS to track the vehicle. Even cameras can be installed to see what, or who may have set off the alarm. These complex types can also be set to give a silent alarm to a portable device such as a phone, a radio, or some monitoring station. An audible alarm may be set to go off at the time, or even delayed a bit, as well as set to sound for a certain period of time. In the case of all types of electronic alarms, they can be set, one way or another, to sound an alarm for any period of time. The older type of mechanical cannot. Any audible alarm will only be heard by anyone that is close to the vehicle, and only for a short distance.
