Secure GSM (ISG) is a revolutionary new product and is designed to protect your Communication from eavesdropping and interception by providing Military Grade security for your confidential mobile phone conversations ISG encrypts the phone call in both directions and on successful connection between parties the phone will display two new information's. Talk: two numbers. Hear: two numbers. These two numbers will need to be used to guarantee you against the "Man-in-the-middle" attack.