During one installation, we noticed lots of calls to premium rate numbers. These calls were being made by an extension number that was outside the extension range and were always calls coming in and then going out on lines.
With further investigation, it turned out that a switch engineer had set himself up as a business with a premium rate service, callers would call in on a local London number and then our customer was paying the cost of the call being transferred out of the building to the premium rate service. The engineer was making a nice little profit. Our customer was able to negotiate a free upgrade from the switch maintainers company, banish the engineer and reduce their call costs. These savings paid for LUMBERJACK.