Here's an article by Michael Yon from August '05
www.michaelyon-online.com/wp/jungle-law.htm
though in that case it wasn't a cellphone but a walkie-talkie

Surprisingly amateurish.

Mobile phone activated detonators must be possible to buy via weapons dealers nowadays.

If you can freely buy cruise missiles, tanks, planes etc, why not this kind of detonator? Too high-tech for the weapons industry?

I always thought it was neat how most technology can be modified for so many diverse uses. The bottom image looks a bit like a detonation device, maybe.

To read a soldiers perspective on this check out... http://www.mopocket.com/2006/02/when_cell_phones_are_the_bomb.php

from a person I know involded in related issues "I assume phones display that message when the network later informs the phone that a previous call to that phone did not connect. The fact that the phone, although being used as an IED component, was recovered intact suggests to me that the signal to the phone was being jammed at the time of the missed call (probably to trigger the IED). Which is probably also the reason the device was recovered undetonated." He later said "The only way to truely defeat IEDs is by convincing the people who are using them to stop using them. Tragically we're still a long way from even trying that strategy."

If you can freely buy cruise missiles, tanks, planes etc, why not this kind of detonator? Too high-tech for the weapons industry?

Think about it.

You can't just go down to the mall and pick up a tank. Neither can the folks that make these things. Bare explosives and phones are far easier to get than real, single purpose weapons.

So why don't "big" weapons buyers use them, and why don't "big" weapons dealers sell them? Because if you have access to a tank, you have access to radio-based detonators that can't be disabled by a commercial phone network when your little plot is discovered.