How can you tell if your alarm company's...

[Major Variola (ret)]

Spooks & Physical IDS:
If you are specifying a "roll your own security system",
you probably want to make a distinction between
building an "alarm company" and a "physical intrusion
detection and logging" system.  With the former you're
hoping to keep your items; with the latter you're
trying to keep your infosec pristine, and the State
Burglars will not take anything. That would look
bad for the Alarm Company they work for (that you
pay to keep your items).

Car Alarms:
If you have neighbors who can see your house, your
homebrew security system can use either strobes to
annoy or fake-flame-lighting to alarm them.

Anon CopCalls:
You could make an anon 911 call using an old
unused cellphone ---the base stations will take
a 911 without subscribing.  You could use a dish
to hit a distant cell.  Though these are jammable.
Best solution is personal IDS that stays quiet.
Of course if you do log an intrusion you have to
sanitize or leave the space.  Keep the housecat
away from the battery-powered ultrasound that
cuts power to the red computer.

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Talk softly and carry a big lawyer.  ---Hunter S Roosevelt