Path: utzoo!mnetor!uunet!husc6!mailrus!ames!pasteur!ucbvax!unccvax.UUCP!dya From: dya@unccvax.UUCP (Edison Carter) Newsgroups: comp.dcom.modems Subject: Connecting a modem to a 2 line phone jack Message-ID: Date: 8 Apr 88 12:44:00 GMT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 56 > 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