Michael Hui <hui@joplin.mpr.ca> (12/28/89)
Lucky us in this city are slated to get ISDN in two years. I believe it requires two twisted pairs to each phone within the house. I wonder whether my current house wiring of standard four conductor cable to each modular phone jack will be adequate, or will the wires have to be replaced with special controlled impedence wiring when I order ISDN? I think the short length of straight non-twisted wire from the lightning protector to the phone jack is short enough to allow reflections to be kept to a minimum, hence allowing the digital signal to be received and transmitted properly.
jackson%sdcsvax@ucsd.edu> (12/30/89)
In article <2440@accuvax.nwu.edu> hui@joplin.mpr.ca writes: >X-Telecom-Digest: Volume 9, Issue 598, message 3 of 9 >Lucky us in this city are slated to get ISDN in two years. >I believe it requires two twisted pairs to each phone within the >house. I wonder whether my current house wiring of standard four >conductor cable to each modular phone jack will be adequate, or will >the wires have to be replaced with special controlled impedence wiring >when I order ISDN? This whole subject has been puzzling me. The standard model for premises ISDN is an NT1 hooked to a station via the two-pair S interface, or to multiple stations (up to 8) via a passive bus version. Since most homes now have multiple phones, the first thought is to have passive bus wiring. But each station is different logically I believe and only one phone can use a B channel at a given time (no "conferencing"). Unless I have some deep misunderstanding, it seems that the simple model will not serve a multi-phone house very well. I suspect that in practice people will choose to buy NT12 units. The NT2 portion of these will effectively be a PBX and in addition can support an R interface (one pair analog) to existing POTS phones for those who don't want to replace all their current phones with $500 ISDN sets and also rewire their homes. Such NT12 units are likely to be expensive, especially at first, and this is another reason why I am pessimistic about ISNDN service catching on for residential use. Dick Jackson