Businesses that have their offices swept for eavesdropping devices should be aware that wiretaps from the phone company's central office cannot be detected. This happens when a particular law enforcement agency, whether it be the NYPD or the FBI, convince a judge that criminal activity might be taking place. They then are able to get a court order to tap the company’s phones.
Whenever the Technical Division of Sherlock Investigations does an eavesdropping sweep to look for bugs and wiretaps, we caution potential clients that if they they are being investigated by a law enforcement agency we will will not do the sweep.
Typically, according to the FBI, they tap a phone at the phone company's central office. They then have the call forwarded to the FBI office at 26 Federal Plaza in lower Manhattan. There, they listen to the phone conversations and record them on to tape. In spite of ads shown on the Internet, when the phone tap is happening at the central office, it cannot be detected.
The Galleon Group, a hedge fund based in New York City, had their offices swept at least twice. The CEO was arrested by the FBI for insider trading last year. In this case, a former employee cooperated with the authorities, which then tapped his, and others, personal cell phones as well as residential phones. It is not clear whether the office of The Galleon Group's phones were actually tapped. If they were tapped, it would have been done at the phone company's central office.