GSM is the most widely used mobile communication system, which provides authenticity, confidentiality and integrity. The encryption however is for air interface only which means that it secures channel till the BTS. This air interface encryption has been cracked and other vulnerabilities like replay and man in the middle attacks have put all the personal and confidential communications at stake. A lot of work has been done on voice encryption over GSM's Circuit Switched Data (CSD) channel. But CSD channel impairments and quality issues have been prohibitive in the realization of a reliable and acceptable solution. In this paper, we propose voice scrambling technique which not only is hard to break but also will be in subscriber's control. We further discuss its performance over the GSM network.