Erna was the inventor of a computerised system for phone traffic. She used her knowledge of symbolic logic and feedback theory to program the control mechanisms of a call centre to use data about incoming calls to impose order on the whole system. The system used computer electronic methods to monitor the frequency of incoming calls at different times. Her invention revolutionised modern communication. She was an important female pioneer in the field of computer science and the principles of her invention are still used in 21st century communication technology.