Editing Wiretapping (section)

===Non-official use===
[[File:TelRecAdapter.jpg|thumb|300px|A telephone recording adapter (in-line tap). The [[Telephone plug|phone jack]] connects to the wall socket while the phone being monitored is connected to the adapter's socket. The [[Phone connector (audio)|audio plug]] connects to the recording device (computer, tape recorder, etc.).]]
Conversations can be recorded or monitored unofficially, either by tapping by a third party without the knowledge of the parties to the conversation or recorded by one of the parties. This may or may not be illegal, according to the circumstances and the jurisdiction.

There are a number of ways to monitor telephone conversations. One of the parties may record the conversation, either on a tape or solid-state recording device, or they may use a computer running [[call recording software]]. The recording, whether overt or covert, may be started manually, automatically when it detects sound on the line ([[Voice-operated switch|VOX]]), or automatically whenever the phone is off the hook.
*using an inductive [[coil tap]] (telephone pickup coil) attached to the handset or near the base of the telephone, picking up the stray field of the [[telephone hybrid|telephone's hybrid]];<ref>{{Cite web |url=http://www.eece.maine.edu/research/gk12/Files%20for%20PM/CrystalKenney/telecoil_module.pdf |title=Telecoil Experiment |last=Kenney |first=Crystal |url-status=dead |archive-url=https://web.archive.org/web/20100613151434/http://www.eece.maine.edu/research/gk12/Files%20for%20PM/CrystalKenney/telecoil_module.pdf |archive-date=2010-06-13 |access-date=2011-12-20}}</ref>
*fitting an in-line tap, as discussed below, with a recording output;
*using an in-ear microphone while holding the telephone to the ear normally; this picks up both ends of the conversation without too much disparity between the volumes<ref>{{Cite web |url=http://www.olympus.co.uk/consumer/2587_TP-7_Telephone_Pick-up.htm |title=An example of an in-ear telephone recording microphone |website=Olympus |url-status=dead |archive-url=https://web.archive.org/web/20120905024651/https://www.olympus.co.uk/consumer/2587_TP-7_Telephone_Pick-up.htm |archive-date=2012-09-05 |access-date=2011-12-20}}</ref>
*more crudely and with lower quality, simply using a speakerphone and recording with a normal microphone

The conversation may be monitored (listened to or recorded) covertly by a third party by using an [[induction coil]] or a direct electrical connection to the line using a [[beige box (phreaking)|beige box]]. An induction coil is usually placed underneath the base of a telephone or on the back of a telephone handset to pick up the signal inductively. An electrical connection can be made anywhere in the telephone system, and need not be in the same premises as the telephone. Some apparatus may require occasional access to replace batteries or tapes. Poorly designed tapping or transmitting equipment can cause interference audible to users of the telephone.{{Citation needed|date=March 2019}}

The tapped signal may either be recorded at the site of the tap or transmitted by radio or over the telephone wires. {{As of|2007}} state-of-the-art equipment operates in the 30–300&nbsp;GHz range to keep up with telephone technology compared to the 772&nbsp;kHz systems used in the past.<ref>{{Cite thesis |last1=Biswas |first1=Debobroto |title=Performance Analysis of Optical CDMA in Transmission Systems |date=August 2009 |degree=Bachelor of Science in Electronics and Communication Engineering |publisher=BRAC University |url=http://www.spyphonetap.com/Debobroto,.pdf |archive-url=https://web.archive.org/web/20161118040431/http://www.spyphonetap.com/Debobroto,.pdf |archive-date=2016-11-18 |url-status=live |last2=Galib |first2=Saad Yosuf |last3=Mamun |first3=Noor Hossain |page=14 |access-date=2014-07-22}}</ref><ref>{{Cite web |url=https://www.private-investigators-uk.com/detectives/how-to-become/introduction-load-coils-bridge-taps/ |title=An Introduction to Load Coils and Bridge Taps |date=2011-07-22 |website=Private Investigators UK |access-date=2014-07-22}}</ref> The transmitter may be powered from the line to be maintenance-free, and only transmits when a call is in progress. These devices are low-powered as not much power can be drawn from the line, but a state-of-the-art receiver could be located as far away as ten kilometers under ideal conditions, though usually located much closer. Research has shown that a [[Artificial satellite|satellite]] can be used to receive terrestrial [[Electromagnetic radiation|transmissions]] with a power of a few milliwatts.<ref>{{Cite book |title=Satellite communications for the nonspecialist |last=Chartrand |first=Mark R. |publisher=SPIE Press |year=2004 |isbn=0819451851 |location=Belingham, WA |page=136}}</ref> Any sort of radio transmitter whose presence is suspected is detectable with suitable equipment.

Conversation on many early [[cordless telephone]]s could be picked up with a simple [[radio scanner]] or sometimes even a domestic radio. Widespread digital [[spread spectrum]] technology and [[Cordless telephone#Security|encryption]] has made eavesdropping increasingly difficult.

A problem with recording a telephone conversation is that the recorded volume of the two speakers may be very different. A simple tap will have this problem. An in-ear microphone, while involving an additional distorting step by converting the electrical signal to sound and back again, in practice gives better-matched volume. Dedicated, and relatively expensive, telephone recording equipment equalizes the sound at both ends from a direct tap much better.