Cellphones on GSM networks has been vulnerable for quite some time. Many meetings I take part in start with everyone removing their batteries from their phone, as a guesture of showing that it's powerless and can't be tapped or tampered with. In those meeting it would be extremely rude not to do that and people wouldn't want to continue the conversation until you also remove your battery.
CDMA is a system almost only used in the US, coverage is usually not better than GSM, and after all, most of the world use GSM systems, go figure for yourself which one is superior.
Should anyone have any illegal shit going on, be sure to stock up on pre paid GSM cards, make your phonecall and then throw away the card, keep doing so, and never use the same number twice, and you have at least made things a little harder to listen in on you or track your whereabouts. But main tip is of course to not do illegail shit at all, period. Except for walking against an occasional red light and maybe speeding a bit every now and then, but those don't count.
