The Extermination Camp Company's Not-So-Secret War

What gave it away?

1. Who rang EXACTLY at the time that a
   notice of extrication regarding
   USURIOUS bondage schemes was being
   drafted?

2. WHO actually demands to be rang late
   enough in the evening when calculations
   were being made?

3. What codes were contained in those
   numbers that were being transmitted
   that what calculating being done had to
   be ceased PRONTO by one interrupting
   message?

4. Where does Indirect Interruptor work?