Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!brutus.cs.uiuc.edu!wuarchive!swbatl!texbell!vector!telecom-gateway From: euatdt@euas11g.ericsson.se (Torsten Dahlkvist) Newsgroups: comp.dcom.telecom Subject: Rotary-dial Encoding Message-ID: Date: 31 Jul 89 08:57:31 GMT Sender: news@vector.Dallas.TX.US Reply-To: Torsten Dahlkvist Organization: Ellemtel Utvecklings AB, Stockholm, Sweden Lines: 59 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 266, message 3 of 9 Talking about which numbers to dial for operator and so on, how many different designs of rotary-dials were there? I'm not talking about "fashion" phones whith strange looks, I mean the encoding of "digit" to "number-of-pulses". I know of at least three patterns and I'm curious as to whether there are more or not and exactly where the different systems have been used. If the subject has been handled before I would appreiciate E-mail with copies of the relevant articles. First of all: the "normal" - the Bell-system, used _practically_ everywhere (n)-dialling; the digit "1" sends one pulse and so on up 'til 9. "0"=>10. Secondly: "Swedish" dialling. Does anyone else use this? (n+1)-dialling; "0" sends one pulse, "1" sends two... "9" sends 10 pulses. Third: "Oslo" dialling (the Norwegian Capital is different from the rest of the country. Historical reasons?): (10-n)-dialling (or is it (10-(n+1))?); The dial works "backwards" and looks quite funny to the newcomer. I'm not sure if the coding is 1=>10, 2=>9...0=>1 or 0=>10, 1=>9... 9=>1. Somebody out there to fill me in? One possible explanation for the "Oslo" system would be that the digits could be located like the hours on a clock face - more familiar to the user. Is this true or just another modern myth? Has this scheme been used elsewhere? (I have an unverified source saying it's been found somewhere in New Zeeland. Correct?) When Sweden went automatic, starting in the 40's I think and finishing in the 60's, the (n+1) scheme was chosen. Two possible reasons have been told to me. Since they are in no way contradictory, they _may_ both be valid and/or just unplanned spin-offs. Or myths. First: The zero was deemed the most "important" digit, beeing (at the time) used to call the operator and already destined to prefix long-distance calls. Also, the zero is (marginally) more frequent than the nine in any set of numbers. If you have a local exchange with (for example) a three digit numbering plan, you'd start by giving the first subscriber number 100 (or 101). You then go on to fill the numbers, but you (probably) never reach 999 until it's time to expand the entire system. This way, the one through (whichever hundreds you reach) will be most frequent followed by the zero and finally by the "remaining" digits. There _may_ be advantages to having a more frequent digit sending a shorter code. Second: By having zero (a single pulse) to reach the operator, a user on a newly converted line could use his old phone (lacking a dial) to reach the operator by tapping the hook briefly. This is probably mythical since phones were at this time telco property and they presumably changed them all at the time of converting the line. There's been a lot of talk about the different small US local admins of early years. Did any of them go automatic or were they all manual? If any went automatic, did they all choose the Bell dialling codes? /Torsten Torsten Dahlkvist ! "I am not now, nor have I ever ELLEMTEL Telecommunication Laboratories ! been, intimately related to P.O. Box 1505, S-125 25 ALVSJO, SWEDEN ! Dweezil Zappa!" Tel: +46 8 727 3788 ! - "Wierd" Al Yankowitz