Ringing Generators Part# Description 90-0496-01 Ringing Generator Upgrade Kit (25 Hz) 90-0496-02 Ringing Generator Upgrade Kit (20 Hz) 90-0347-03 External Ringing Generator Assembly (25 Hz; 2 ringers; redundant mode) 90-0347-04 External Ringing Generator Assembly (20 Hz; 2 ringers; redundant mode) GO TO OUR HOMEPAGE - CLICK You've come to the right place for High quality, Newbridge products!     NationalDataMux 2002. - All products, logo's and brand names mentioned are trademarks or registered trademarks of their respective owners.