dave@stcns3.stc.oz.au (Dave Horsfall) (05/29/90)
In article <7743@accuvax.nwu.edu>, julian@bongo.uucp (Julian Macassey) writes: | I believe that Aussie phones work the same way. | British Telecom Auxiliary Jack Wiring | British phones have three wires. There are two wires A & B (Tip & | Ring) coming into a house. There is no protector. In the primary jack | in the house is a 2 uF capacitor. On the end of this cap is the third | wire. The AC ringing signal is fed to the phone on this wire and its | DC counterpart. Australian phones are similar, but not quite the same. My memory is getting hazy, but this is what I recall: The pair from the exchange appear on pins 2 and 6 of a (comparatively) enormous 4-pronged device (2 conductors per prong, with a keyed dummy). The blocking capacitor is installed in the "first" telephone in the system, with the extensions being wired in series/parallel with three conductors (bells in series via pin 3, transceivers in parallel) and the capacitors are bypassed on the extensions. Typically, the "first" handset has its plug screwed into the jack, so it cannot be removed. In these days of electronic ringers, the point is moot. You could always tell when someone (illegally) wired their phones; they either tinkled when somebody dialled (mis-wired), or they didn't ring when the main phone did (bell disconnected to stop the Telecom Thought Police from investigating a sudden change in REN...). Nowadays, the demarcation point is the first telephone jack in the premises (if a household) or the termination panel (if business/flats), and you can plug in what you like after that (but must still be approved). Other pins had various uses: 1 & 5 were typically used for modems, etc (2 & 6 went to modem, phone went to 1 & 5 from modem), and I believe pins 3 & 4 were remote bells. There were many configurations. Dave Horsfall (VK2KFU) Alcatel STC Australia dave@stcns3.stc.oz.AU dave%stcns3.stc.oz.AU@uunet.UU.NET ...munnari!stcns3.stc.oz.AU!dave