Radio Shack sold one ages ago and then X10 took it over. I have the original Radio Shack version and even though it's 90s technology, the system works incredibly well. It appears X10 recently updated the system completely changing the look but I think it still operates the same...I have a few of the newer accessories and they are still compatible with mine.
You record a message on the base station and program in multiple numbers for it to call. I have motion sensors on each level of my house and one in the garage plus several door sensors. The base station has a pair of built sirens and I have another remote module which just plugs into a wall outlet with 4 sirens. When they go off, it's loud enough to wake the dead. I have several remote light modules which flashes lamps through out the house. The master remotes can also turn all the lamps on/off or dim. The key chain remote sets the system from outside the house and can control one lamp. Master remote can arm "away" or "home". If armed in home mode, only the door/window sensors are activated and not the motion sensors.
If you don't want to carry a key fob remote, you can have timed exit and entry.
When the alarm calls your cell phone, it'll play your message and you can press 0 which will silence the sirens and allow you to listen in to your house through the base station's built in mic. If you have more than one number programmed in, such as a neighbor or relative, it'll continue to call them too.
The base station has a back up battery in case of power outage. The remote sensors use AA and AAA batteries and they last for YEARS. It's been nearly 5 years since I replaced the batteries in my motion sensors. If any sensor doesn't check in after so many minutes, its specific zone light flashes on the base station and it'll warn you of an error when you go to arm the system.
In over 15 years, I think I've had maybe 2 false alarms.
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$200 bucks will get you a pretty decent starter system and you can add onto that if needed. I've also bought quite a few accessories dirt cheap on ebay.