Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!bionet!apple!usc!elroy.jpl.nasa.gov!gryphon!vector!telecom-gateway From: sandy47@ucsco.ucsc.edu (90784000) Newsgroups: comp.dcom.telecom Subject: Re: While Phone Rings, Charges May Begin Message-ID: Date: 31 Jul 89 14:53:43 GMT Sender: news@vector.Dallas.TX.US Reply-To: /dev/null Organization: University of California, Santa Cruz Lines: 28 Approved: telecom-request@vector.dallas.tx.us X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.dallas.tx.us X-TELECOM-Digest: volume 9, issue 269, message 4 of 8 In article pnet01!pro-sol!pro- newfrontier!pro-nfmail01!pro-harvest!pro-palace!r. writes: >You said in your message that, through playing with your line loop resistance, >that you could receive a call, while your switch was under the impression that >you had not answered.. This was a method used by Phone Phreaks in the early >80's to avoid billing. A phreak would put a 'colored' 'box' (they were >labeled by colors) on his/her line and receive calls from other phreaks at the >phone co's expense... > >- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Actually started in the late '60s. There was an article in Ramparts Magazine which gave actual details, including Radio Shack part numbers for building a "Yellow" box. Basically a resistor to be switched in at time of ring receipt to disable call charging (since the telephone had never been answered). "Blue" box details were worked out from the Bell Systems Technical Journal article published in the '60s which explained the inner workings of the new DTMF and MF systems. In the '70s "Captain Crunch" popularized this and added the computer twist. Go to your local US Government Depository Library (many public libraries and most university libraries fall into this category) and look up the Code of Federal Regulations for Telecommunications (several volumes). Part 68 has an interesting section on "Billing Protection" which deals with both the MF tones generated by "Blue" boxes and the impedance shifting done by "Yellow" boxes. But don't USE the information illegally or you'll be placed in a "Gray" box with steel bars :-).