I find it interesting that a security professional would think that the type of phone you use would protect you from prying eyes. Moreover recommend a standard phone and not something like sectera. A phone is only as strong as the network it is on and gsm has been hacked and encryption tables published. I believe phones like sectera use only a 3g connection for voice which takes care of the gsm problem.

Granted it would take a small fortune to acquire the necessary equipment to be able to do it, when your talking medical and patent information worth possibly hundreds of millions of dollars, it's really not that much.

The wireless access points are also a vulnerable point, for instance if you use a blackberry, considered for some time to be the standard for business security, they use their own access servers regardless of the carrier their on. Their encryption was so strong that the uae and saudi government looked to ban them because they couldn't hack their network,

Backdoors ever since the implementation of CALEA in the US and programs like carnivore, echelon and narusinsight nothing is off limits.

Bottom line ...if it is something that is that important that no one else can see or hear dont use a cell phone.