Well when it comes to vehicle recovery systems (LOJACK is a recovery system, not a security system) as the best B&E auto man at the Detroit Freeway post of the Michigan State Police, also a dispatcher therein, I perhaps am the man to answer you.
First, as noted LOJACK won't stop anyone from swiping your wheels... It just helps you get them back, sometimes
There are basically 5 systems I'm familure with.. Lojack is one of them, and is unique, here is how it works.
When you discover your truck is no longer where you parked it, you notify the police, they process your report and hopefully promptly eneter the vehicle in their statewide police computer and into the National Criminal Information Center computer (NCIC) Lojack monitors NCIC entries and when it sees the unique Vehicle Identification Number of your vehicle, it sends a radio signal to your truck, (hopefully) telling it to alarm itself. The truch then begins broadcasting an occasional BEEP, which contains it's unique LOJACK identification number. If a police car equiped with a LOJACK receiver happens to pass close enough the receiver in the police car gives out a signal (Beep of it's own) and displays your ID number. Then good things happen.
However if you are in an area that does not subscribe to LOJACK (Not all police departments are equiped to track) or if there is no lojack activation tower in your area... It does not work.
But the major shortcoming of Lojack is that YOU have to discover your truck gone
I believe with LOJACK you pay a one time fee (instalation)
Now the other systems include ON GUARD (Ford) ON STAR (GM), Teletrack (Not sure who owns that now, possibly cingular) and Cingular's vehicle recovery system. With all these systems you pay an instalation fee and then a monthly monitoring fee (After an initial FREE period)
For the most part these are all cell phone based but may use other technology (Such as GPS) as well, in these cases the system is a combination recovery and security system. Here is how they work, NOTE: some systems have "Options" I'm going to describe the two I know best, ON-Guard/Star, which are nearly identicall in this case (Some of the features are options on the other systems)
When the theif starts your car in a non-authorized manner (Without a key, or without disabling the on-board security/alarm system) it automatically activates the ON-Guard/Star system, the system then attempts to contact it's monitoring stationg. The station, which has your contact info on file, will then attempt to contact you, Since they know the location where you car was parked (Home, Church, Doctor, Store, Airport,Theater parking lots) they have an idea of where to call, or they can try your cell... If they succeed you can advise if the car is moving with, or without permission. If not they call the police for you and instruct you on where to make the report.
If they are unable to contact you, and the person in the car does not have the proper password,, they call the cops
They have tracking report, showing where you car is every few seconds, they can tell the police and when the police are in position and give them the word they can lock your car (truck in your case) and kill the engine
TRUE STORY:
Man owned a Caddalic Esclade (Super SUV) and it was stolen.. Local PD put out a BOL (Be On Lookout) and I read it at least 3 or 4 times,,, no place did they mention On-Star. I sent them back a message which went somethin like
Uh, you know that all Esclades come with On-Star, among other things it's a vehicle recovery system 1-800-xxx-yyyy (or whatever the phoen number is) less than 15 minutes later we knew where the Esclade was parked. and in another 15 we had recovered it.
Other advantages of On-Guard/Star are "i'm lost" service (Since they can pinpoint you they can direct you) and medical assistance (Panic button), they also monitor the vheicle sensors for air bag deployment and can call you, and if you dont' answer the police and EMS should you crash. As a police dispatcher I've gotten more than one of these calls.
If you lock your keys in the truck, they can help you.. If you forget where you parked, no problem.
Just one word of caution .... If you forget to pay.. They assist the repo folks too