Gigaherz Forum

Can you hear me now? No. Good!
Devices to jam the downlink frequencies on various cellular telephone systems. Prevents the cellular phone user from sending or receiving phone calls within the small jam radius. Advanced electronic and RF engineering technical skills will be required.

http://gbppr.dyndns.org/PROJ/mil/celljam/

This makes sense,
one is against all electro-magnetic radiation on the other hand suggests to build jamming devices which radiate RF energy too. First of all, to build these requires fortunately a lot of RF engineering skills. Thereafter it has to be said that it is highly illegal to transmit RF energy without being in possession of a corresponding licence, which is issued by the BAKOM.

Regards

Otto Normalverbraucher