Editing Blue box (section)

===Decline===
The ultimate solution to the blue box vulnerability was to do what the phreakers thought impossible and upgrade the entire network. This process occurred in stages, some of which were already well underway in the early 1970s.

The [[T-carrier|T1]] system was developed beginning in 1957 and began to be deployed around 1962. It digitized the voice signals so that they could be more efficiently carried in high-density connections between exchanges, carrying 24 lines on a single 4-wire connection. Depending on the network layout, the user might no longer be connected directly to a tandem, but instead to a local office that forwarded the signal over a T1 to a more distant exchange that did have the tandem. Simply due to the way the system worked, the supervisory signals had to be filtered out in order for the digitization of the analog signal to work. Recall that the 2600{{nbs}}Hz tone was not dropped from the trunk until the line was connected all the way and would be mixed with other tones like the ringing or busy signal; when used over a T1 this tone mixed with other signals and caused a problem known as "quantization noise" that distorted the sound. These tones were thus filtered down on either side of the T1 connection. Thus it was difficult to blue box in such an environment, although successes are known.

But blue boxing was eventually eliminated entirely for unrelated reasons. In the existing tandem-based network, completing a call required several stages communicating over the trunk line, even if the remote user never answered the call. As this process might take on the order of 10 to 15 seconds, the total wasted time across all of the trunk lines could be used to carry additional calls. To improve line usage, Bell began the development of the [[Number One Electronic Switching System]] (1ESS). This system performed all the calling and line supervision using a separate private line between the two offices. Using this system, when a long-distance call was placed the trunk line was not initially used. Instead, the local office sent a message containing the called number to the remote exchange using this separate channel. The remote office would then attempt to complete the call, and indicate this to the original office using the same private line. Only if the remote user answered would the systems attempt to find a free trunk line and connect, thereby reducing the use of the trunk lines to the absolute minimum.

This change also meant the signaling system was available internally to the network on this separate line. There was no connection between the user lines and this signaling line, so there was no route by which the users could influence the dialing. The same rapid reduction in prices that made the blue box possible also led to the rapid reduction in cost of the ESS systems. First applied only to their busiest connections, by the 1980s, the latest [[4ESS]] models and similar machines from other companies were deployed to almost all major exchanges, leaving only corners of the network still connected using tandems. Blue boxing worked if one connected to such an exchange, but could only be used end-to-end if the entire network between the two endpoints consisted only of tandems, which became increasingly rare and disappeared by the late 1980s.

Analog long-distance transmission systems remained more cost effective for the long haul circuits until, at least, the 1970s. Even then, there was a huge installed base of analog circuits, and it made better economic sense to keep using them. It was not until competitor Sprint built its all digital, "quiet", network, where "you could actually hear a pin drop",<ref>Archived at [https://ghostarchive.org/varchive/youtube/20211211/qiJOdBxlhhA Ghostarchive]{{cbignore}} and the [https://web.archive.org/web/20171115031219/https://www.youtube.com/watch?v=qiJOdBxlhhA Wayback Machine]{{cbignore}}: {{Citation|title=Sprint Phone Service commercial 1986 pin drop|url=https://www.youtube.com/watch?v=qiJOdBxlhhA|language=en|access-date=March 16, 2021}}{{cbignore}}</ref> that AT&T took a multi-billion dollar write-off and upgraded its long-distance network to digital technology.

The phreaking community that had emerged during the blue box era evolved into other endeavors and there currently exists a commercially published hacking magazine, titled ''[[2600: The Hacker Quarterly|2600]]'', a reference to the 2600{{nbs}}Hz tone that was once central to so much of telephone hacking.<ref>{{Cite web |url=http://www.2600.com/wall/24-05-2016 |title=NEW 'Off the Wall' ONLINE &#124; 2600 |access-date=May 31, 2016 |archive-url=https://web.archive.org/web/20160602035336/http://www.2600.com/wall/24-05-2016 |archive-date=June 2, 2016 |url-status=dead }}</ref>