Thank you very much.<br><br>A firm  from Turkey called Aselsan 
succeeded  to make encrypted conversation over GSM. It transfers the 
voice data  (1.2 kbit/s ) with Synthetic <br>Voice Modulator technology.<br><br><a href="http://www.aselsan.com.tr/images/dokuman/HC/AHSPD/kripto/2110/2110_whitepaper_ING.pdf" target="_blank">http://www.aselsan.com.tr/images/dokuman/HC/AHSPD/kripto/2110/2110_whitepaper_ING.pdf</a><br>