Editing Phreaking (section)

===2600 hertz===
[[File:Cap’n Crunch, Spielzeugpfeife (2600 Hz).jpg|thumb|A [[Cap'n Crunch]] breakfast cereal toy produced a 2600 hertz tone.]]
{{Main article|2600 hertz}}
The origins of phone phreaking trace back at least to [[Bell System#Nationwide Monopoly|AT&T]]'s implementation of fully automatic [[telephone switches|switches]]. These switches used [[tone dialing]], a form of [[in-band signaling]], and included some tones which were for internal telephone company use.{{citation needed|date=July 2014}} One internal-use tone is a tone of [[2600 Hz]] which causes a telephone switch to think the call had ended, leaving an open carrier line, which can be exploited to provide free long-distance, and international calls.  At that time, long-distance calls were more expensive than local calls.<ref name="robson"/><!-- Sterling also has a description of this somewhere -->

The tone was discovered in approximately 1957,<ref name="robson">{{cite web|url=https://garydrobson.com/2014/06/03/the-origins-of-phreaking/ |first=Gary D. |last=Robson |publisher=Blacklisted! 411 |date=April 2004 |title=The Origins of Phreaking}}</ref> by [[Joybubbles|Joe Engressia]], a blind seven-year-old boy. Engressia had [[absolute pitch|perfect pitch]], and discovered that whistling the [[piano key frequencies|fourth E above middle C]] (a frequency of 2637.02&nbsp;Hz) would stop a dialed phone recording. Unaware of what he had done, Engressia called the phone company and asked why the recordings had stopped. Joe Engressia is considered to be the father of phreaking.<ref>{{cite web | url= https://delontin1.wordpress.com/tag/hacking/| title=COMPLETE HISTORY OF HACKING| last1=DELON| date=February 27, 2008| website=Hacking &#124; LEMNISCATE| access-date= 2014-12-25}}</ref>

Other early phreaks, such as "Bill from New York" (William "Bill" Acker 1953-2015), began to develop a rudimentary understanding of how phone networks worked. Bill discovered that a [[Recorder (musical instrument)|recorder]] he owned could also play the tone at 2600&nbsp;Hz with the same effect. [[John Draper]] discovered through his friendship with Engressia that the free whistles given out in [[Cap'n Crunch]] cereal boxes also produced a 2600&nbsp;Hz tone when blown (providing his nickname, "Captain Crunch"). This allows control of phone systems that work on [[Single-frequency signaling|single frequency]] (SF) controls. One can sound a long whistle to reset the line, followed by groups of whistles (a short tone for a "1", two for a "2", etc.) to dial numbers.<ref>{{cite book | last = Lapsley | first = Phil |author-link=Phil Lapsley | title = Exploding the Phone: The Untold Story of the Teenagers and Outlaws who Hacked Ma Bell | publisher = Grove/Atlantic, corporated  | date = 2013-11-02  | location = New York | isbn =  978-0802120618}}</ref><ref>Lapsley, Phil (February 5, 2013). [https://www.wired.com/2013/02/exploding-the-phone/ "Exploding the Phone: The Untold Story of the Teenagers and Outlaws Who Hacked Ma Bell"]. ''[[Wired (magazine)|Wired]]''.</ref>