there are so many variables to this- do you live in the city or country? If you live in a rural area where it is going to take the police 30 minutes to get to your house, what is the point of an alarm? If are are looking for an audible alarm intend on scaring away a thief, be prepared for some pissed off neighbors cause every time someone enters the code wrong, or there is a power outage, or numerous other false alarms that blaring noise is not going to be welcomed. Plus, think about this- on all of those TV commercials you see for (former) Brinks, someone tries to break in, the alarm goes off, immediately a phone call is made where the homeowner answers and the Brinks operator says he will call the police. The time frame they are indicating is untrue. It may take several minutes for the alarm company to call you and in that time, you should be calling 911 and talking directly to the police- why have a middle man? The police are going to want a direction of travel, a description of the suspect, all things the alarm company operator is not going to know. Good deadbolts, common sense and motion activated lights and cameras at the homes entry points are better in my opinion.
many many years of dealing with alarm companies while working as a police dispatcher.