Earlier this week we showed you Gi & Di's Mobile Security Card for secure email communication. Another attention getting BlackBerry solution that surfaced at WES 2009 was from Cellcrypt. They provide end-to-end encryption for voice calling to ensure conversations remain secure at all times.
You can watch the video above for an overview and click over to Cellcrypt's detailed explanation page for a full run down of how it works (uses an encrypted mobile protocol which runs over IP). Using CellCrypt adds a few seconds to the calling process, but if you're in an industry where secrecy is of the utmost concern, then this is definitely a solution to look into.