[docbnj]

Very clever, but ...
I guess the cat is out of the bag. This is terrible. I assume that readers are thinking what I am thinking.

[Gorzaloon]

Very clever, but ... I guess the cat is out of the bag. This is terrible. I assume that readers are thinking what I am thinking.

Relax. THEY have been using cellphone ringers to trigger realys for years.

The good thing is they never published, patented them or sold them, so she will not have Prior Art problems.

[ChadGore]

Dependable cell service would be the biggest problem. Here's how I would do it:

Use an inverter/transformer to plug in a phone charger.

Use the ringer on the phone to close a relay to the starter.

Mount it all under the dash, or stuffed away within the crew cabin to prevent the elements from getting to the phone.

You could block all calls on the receiving phone, so that it only receives from one phone number.