[Zone-MR]

What can I say... the wold has a severe excess of idiots.

Firstly, jamming cellphones on a large scale is near-enough impossible. The spread-spectrum method used to transmit GSM signals makes them almost immune to interference. Of course there are active systems which simulate fake base-stations, but they have a limited range unless you feel like microwaving everything and everyone in the nearby vicinity. Wouldn't it be much easier to ask cellphone operatiors to disable their services temporarily, rather than devising methods to jam them? I'm sure cell operators would be more than willing to cooperate in cases where the govermnent has actual evidence that a bomb detonation via cellphone is imminent (and they could still permit access to emergency lines).

Secondly, unless they plan to do away with celphone communication in an entire area permanantly, the jamming ability is usless. Had they had the technology, the Madrid bombings would not have been prevented. You'd need to know for certain that a terror attack is going to occur. You can't just keep the entire spectrum blocked for good measure.

Thirdly, if this 'defense' does become commonplace, terrorists will use timers, or a long-range radio on a different frequency band. The only reason cellphones are used for detonation atm is because it's cheap and convenient. Anyone can obtain an el-cheapo cellphone with a tarrif with no contract, and connecting the RI (Ring indicator) pin to a detonator circuit via a simple relay or transistor is trivial.