On Jul 1, 2:43 am, "JohnK" <[email protected]> wrote: > Er, are we being sloppy here rounding 17 to 20? Or do the weirder countries > [ie not Australia :-)) ] use 20 ? I thought it was bad enough rounding 16 > 2/3 [16 and two thirds] to 17 !
Standard (individual and 2-party) lines used ringers nominally configured for 20Hz which would actually operate on a relatively wide range of frequencies. 2-party operation was done by sending ringing voltage between one wire of the phone pair and ground for the first subscriber, and from the other wire to ground for the second subscriber. More complex party line configurations used frequency-selective ringers. It was possible to get up to 8 customers on one pair, with 4 selective ringers on each half of the phone pair. Beyond that, or on equipment that didn't support frequency-selective ringers, you'd know if the call was for your number based on the ring pattern. Old equipment normally wasn't upgraded if it didn't already have selective frequency support, using the logic "the customer is using a party line to reduce their costs - why should we (the phone company) spend money to make their life easier?" When making calls, 4 parties could be identified (ring, tip, tip + 1K, tip +2.65K) if the switching equipment supported it (see above for why it often didn't). If the equipment didn't support it, any direct dial call would go to an intercept operator that would ask you for your number. And of course, if you were on a non-dial party line, you had to tell the operator both the number you wanted to call and the number you were calling from. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
