A Hardwired Wiretap occurs when physical access is gained to a section of wire that carries the signal (i.e., a telephone line).

A second set of wires is connected (typically via an isolation or slave device), and the signal is then bridged back to a secure location.

When this type of wiretap is discovered, it is relatively simple to trace back to the listening post. This type of wiretap, when discovered, is fairly easy to trace back to the listening post.

A “soft wiretap” is a change to the software that runs the phone system. This can be done through the phone company or, in the case of a business, through the PBX. A soft wiretap is the preferred method of tapping a phone because it is difficult to detect in the phone company’s system. It may also be referred to as a REMOBS (REMote OBServation), DATU, ESS, or translation tap. This type of tap is popular among large law enforcement agencies, intelligence agencies, larger corporations, and hackers who find it relatively easy to gain access through maintenance software.

A recording wiretap is simply a tape recorder wired into the phone line, which is very easy to detect during a TSCM inspection.

The tapes must be changed on a regular basis, similar to a hardwired wiretap. This is extremely popular among amateur spies and private investigators, but they are extremely dangerous to use, and many eavesdroppers have been caught red-handed when they arrived to service their illegal recorders. Digital recorders are replacing tapes, but as with tape recorders, the data must be retrieved by someone.