When it comes to securing your home, you can choose to do it yourself with a variety of products or go with a company that will pretty much handle everything. Regardless of what you choose, if you want police response to an alarm you will need to go with an alarm monitoring service. If you look around at the options available to you, there are big names such as ADT and smaller local or unknown companies. Chances are, the smaller companies serving locally are just authorized re-sellers and/or local monitoring services rather than small independent companies. It is important to make this distinction because you could have great customer service from the local company when purchasing and installing your alarm yet be met with horrible service once the deal is done and you no longer work with them. This can go the other way as well since the local company is obviously getting paid to lock you into a three-year contract with the bigger company and you are in effect paying a middleman.
The actual monitoring service you pay for is relatively simple. If an alarm goes of in your house, whether it is a window alarm, a door alarm, or other type of sensor (fire etc.) a dispatcher at the alarm service will call you. They generally have a policy that if you do not answer the phone or answer the phone and request help, they will immediately contact the police or fire department (depending on the emergency) and have them send help. It is important to note that the alarm does not automatically send the police itself, the monitoring service does. This has raised questions with many people since they feel that by the time the call is missed and the police are sent, it is going to be too late. This is a personal decision and it is important to remember that the mere fact that an alarm sounds can deter many criminals before any crime (beyond breaking in) has been committed.