[I've played around with an expensive version from another vendor. It appeared to function (my dual mode CDMA PCS phone quickly became inopperative). Range was limited due to low power output (about 12wm). The circuits are very simple and the addition of an inexpensive 10-12db power amp stage for both the 1900 and 800 MHz bands would extend effective ranges to 50m or so. This is a good candidate for anonymous cash sale. It could become the next teen gota have prank product (the laser pointer "dotting" thing is about played out.)] Jamming technology blocks cell phone rings By Reuters November 21, 2001, 10:00 a.m. PT HONG KONG--A Hong Kong company hopes to sell signal jamming technology, previously used by the military to thwart lethal missiles, to block annoying cell phone calls in places such as hospitals, places of worship and restaurants. http://news.cnet.com/news/0-1004-200-7942522.html?tag=lh