The receptionist was instructed to call a vendor. Using the vendor's invoice as the source of the phone number she began calling. Each time she called, her phone would ring. When she answered, no one was there. This continued throughout the morning. When later asked if she reached the vendor she explained what was happening and demonstrated for her superior. He noticed that the phone number she was calling (which was on the vendor's invoice) WAS THEIR OWN PHONE NUMBER! She had spent an entire morning calling herself.