The Call 9-1-1 Necklace

I want to make a new product: a necklace that when smashed/broken will call 911. There are obviously useful applications for such a necklace.

It's going to be tricky-- a tiny SMT-packaged microcontroller will probably be suitable (like the ATtiny45) and I dunno the first thing to make a microcontroller connect to a phone line or dial a call. Does anyone have ideas on a first-version prototype? I am hoping to breadboard it once I get the idea down.

My grandmother has one of those.

I'd suggest doing it like that company did by having a base station that connects to a land line and wirelessly to the button. Then you don't have to deal with cell phone contracts and stuff.

You could have nothing but an xbee in the button, since those have a few digital i/o pins.

You could get a Normally Closed switch that completes a circuit. When the switch is broken it will trigger an alarm, in this case I would recommend rewiring the Life Alert 911 Phone (, so that the switch activates the 911 button.

You could have a wireless radio transceiver send a message to its pair connected to an Arduino and a 3G shield. You can then send a pre-programmed SMS to whomever upon the event trigger.