ANALOG DTMF ENCRYPTION
Original Publication Date: 1995-Nov-01
Included in the Prior Art Database: 2002-Apr-03
In current analog trunking systems, Motorola provides a secure l2kb option. This option will give a user secure voice communications. A current prob- lem with many 12kb secure systems is that the DTMF tones can not be encoded into 12kb secure. The analog systems today solve this problem by "fall- ing back" to non-secure mode to transmit the DTMF tones. Anyone "listening" to the communications can "pick" the DTMF tones up and decode them with off the shelf equipment into numbers. These numbers can be phone numbers, credit card num- bers, calling card numbers, or access numbers. With no way to secure this information, users who think they may be transmitting their access numbers securely are not.