In December of 2009 we heard that the encryption used for GSM voice calls had been hacked. Mobile carriers have a more secure GSM algorithm they can use to secure calls and they maintain that carriers using the hacked GSM encryption are still more secure than we might think. If you are the sort that wants really secure communications GO-Trust has announced the KingCall microSD card.
The KingCall card is a micro-SD card with a smart card "in-chip" that encrypts both voice and text when used with VoIP services. All of the encryption and decryption is handled on the microSD card meaning there is no performance impact for the smartphone.
The card can be used in any unmodified 3G smartphone. The fact that all of the encryption and decryption is done on the microSD card also means the encryption keys aren’t subject to theft using Trojans or viruses. The card will be shown off on devices running on the Sprint network using Windows Mobile and on T-Mobile devices at RSA in San Francisco soon.