And any commercially available "secure phone" won't be as good as the encryption the DoD can slap on one. I feel sure the tools that we used to hack Merkel's Blackberry are available to intelligence services around the world to do to us as well.
The trouble with commercial cell phones is the technology at its base. The phone digitizes the users voices and sends the call as data and not as an analog signal like the landlines. With the commercial cell technology the cell tower can read that data. Nominally this allows them to check signal quality and route the call to the other end. It also allows them access to the contents of the data, in this case the users voice. So unless the phone can encrypt the users voice and that data is sent to the other end without breaking down the encryption its not secure.
This requires an application on the phone separate from the call functionality. So instead of making a cell call you would use the application to make a call. This isn't foolproof, since the phones microphone is easily compromised and could route the audio to any destination.
Its more than encryption since the sending and receiving device also have to be secure.