I’ve known for some time that there are special mobile and fixed line phones out there which can encrypt calls from end to end. I recently met Dr. Björn Rupp, CEO of GSMK, a company developing such phones. While probably not of much interest for the average person, there are a lot of people out there from politicians, police, top level managers, etc. who want to be sure their call is not intercepted. Not by the government, not by a secret service, not by tech savvy reporters or nosy mobile phone company employees. All these people can get access to normal mobile calls as the only interface over which the call is encrypted is between the mobile phone and the base station (GSM) or the radio network controller (UMTS). Over all other interfaces, the call is sent without any encryption and core networks even contain standardized interfaces for law enforcement agencies to tap into calls.
The phones developed by GSMK encrypt calls end to end by establishing a data connection between the two ends instead of a normal voice call and then use a strong encryption algorithm to ensure eavesdroppers have no chance. Dr. Rupp’s business card is also the first one I’ve ever seen which contains his PGP key ID and fingerprint. Also, they’ve published the source code of their encryption algorithm on their website, so no security through obscurity. Cool stuff, I am impressed!