kwe@BU-CS.BU.EDU (Kent W. England) (03/31/88)
In article <1218@sjuvax.UUCP> bellcore!bpa!sjuvax!cc743810@rutgers.edu (Chuck(ster)) writes: > >I have a Hayes 1200b modem installed in an AT&T 6300 PC, and the office >that it is in has a 2-line phone. The phones wall plug is not the >standard size, it is wider. How do I connect the modem to the 2 line >wall jack? If it's a wider jack it is probably an eight-wire or RJ-45 jack. AT&T calls the shots for wiring a 4 pair jack and they maintain the same pin-out for the first and second line pairs, although pair one is still pair one, pair two [the second line] is pair three on the punchdown. If you want to connect to the first line, I think a regular one or two pair patch cord should work. If you want to connect to the second phone line you need a little adaptor to swap the first and second pair. I think these are common at Radio Shack. You should be able to plug a cord designed for the narrow jack into the fat jack. Here's the two different pin-outs: RJ-11 (narrow jack) what the modem wants 1 2 3 4 5 6 Pr R2 R1 T1 T2 Pr T&R refer to tip and ring [like + and -]. I may have the pin number ordering reversed. The number refers to the ordering of the pair on the punchdown. 1 is the first line and 2 is the second line. Pr is for power (to light your Princess phone :-) RJ-45 (wide jack) what the phone is wired for 1 2 3 4 5 6 7 8 P2 P2 R3 R1 T1 T3 Pr Pr Pair one is for voice, the second and third pair for data and the fourth pair for power, but you can use the third pair for the second phone line. Is this too confusing? Try a standard patch cord and see if it works, you might have trouble swapping tip & ring, although I'm not sure but that the modem will work either way. > (It it not necessary to have the phone operational when >the modem is in use - but it would be nice if it is an easy to do >hack). That will only work if the modem is on line 2 and the phone on line 1, of course. Kent England, Boston University
syap@ur-tut (James Fitzwilliam) (04/07/88)
Even before this issue came up, I was going to post an article wondering why modem manufacturers don't provide some way of deciding whether data calls will be placed on Line 1 (Red/Green) or Line 2 (Black/Yellow). All that would be necessary would be a DPDT switch, or a relay and a transistor activated by one of the "future use" or "user-definable" registers. My Practical Peripherals modem (which I love, by the way -- inexpensive but not cheap :) has a register setting for "telephone jack type" which I was hoping would be such a selector. All it does, though, is create an off-hook condition for _both_ lines rather than just line 1 during a data call; the connection is still on line 1. The manufacturers are obviously aware of multi-line telephone systems. All units I have seen pass all four wires through for your telephone hookup, and my deceased Popcom had an 8-wire jack and generated 1A2 key telephone signals. Of course connection to the Red/Green pair should be the default, but let's think a minute here: If I add a second line to my house, it will go on Black/Yellow. If this line is for my computer, I won't want the modem connected to line 1 anymore, so I make or buy some sort of adaptor. If I have two lines for my business, I can't choose which line to use for data calls without repatching (or making a phone A/B box). This seems kludgy to me, especially when some available modems do everything but walk the dog and do the dishes. Anybody want to comment on this? Does anyone know of a modem which lets you select line 1 or line 2? James domain: syap@tut.cc.rochester.edu path: rochester!ur-tut!syap "Piano is my forte" (-: GEnie: FITZWILLIAM ========================================================================
dya@unccvax.UUCP (Edison Carter) (04/08/88)
> kwe@BU-CS.BU.EDU (Kent W. England) writes: > > bellcore!bpa!sjuvax!cc743810@rutgers.edu (Chuck(ster)) writes: . . . > >standard size, it is wider. How do I connect the modem to the 2 line > >wall jack? > Here's the two different pin-outs: > RJ-45 (wide jack) what the phone is wired for > 1 2 3 4 5 6 7 8 > P2 P2 R3 R1 T1 T3 Pr Pr > Pair one is for voice, the second and third pair for data and > the fourth pair for power, but you can use the third pair for the Sorry, but this is an extremely sore point with me. The RJ45 jack is obstensibly NOT configured for this "pair one, pair two" business. Pins 1 and 2 of the RJ45S jack are UNDEFINED. Pin 3 is M1, a contact closure for exclusion key telephones, to pin 6, M1C. Pin 4 is Ring, pin 5 is Tip, of the line connected to the PSTN. Pin 7 and pin 8 define a programming resistor which, upon correct measurement of the loss of the subscriber loop, tells the modem (in programmed mode) what transmit level to emit so that -12 dBmV arrives at the CO. RJ41S is similar, but pins 1 and 2 represent Ring and Tip (respectively) with a fixed loss loop pad inserted in the circuit. Pins 4 and 5 carry the unmodified ring and tip, respectively, of the same PSTN circuit. There is no such thing (although people do it frequently) as a two line RJ11W/C jack. The two line equivalent is RJ14W/C. The wiring sequence is up to the customer. Pins 1 and 6 are not defined. However, as a practical matter, the RJ11W/C plug will even (usually) pick up T and R (1) of even the 8 pin jack. Be forewarned, there are other configurations of 8 pin jacks which do neat things like remove a shorting bar when a plug is inserted, operate with the exclusion key, etc. The only real flamage is the misunderstanding which most (including telephone company personnel) have about the data jacks, and the perpetual misinformation campaign - which the original poster(s) aren't a part of - about the RJ41/45 data jacks. They are defined, and have a specific function in life. My source is Title 47, United States Code of Federal Regulations, Part 68, Appendix A, Subpart F, FCC Rules and Regulations, 41 FR at 28699, published July 12, 1976. David Anthony WLQV Detroit