Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site unccvax.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!genrad!decvax!mcnc!unccvax!dsi From: dsi@unccvax.UUCP (Dataspan Inc) Newsgroups: net.dcom Subject: Re: RJ-41S and RJ-45S Message-ID: <125@unccvax.UUCP> Date: Mon, 21-Jan-85 14:46:59 EST Article-I.D.: unccvax.125 Posted: Mon Jan 21 14:46:59 1985 Date-Received: Thu, 24-Jan-85 19:11:25 EST References: <90@tove.UUCP> Organization: UNC-Charlotte Lines: 49 (now, to dig out the FCC Rules and Regulations) Dreaded jack RJ41S possibly specifies a tariff concerning the SLIC card and the use of certain compressing devices at the C.O. , but I can't confirm this. We installed (and install) 9600 bps dial-through UDS modems in people's homes all the time (doctors) and it seems that specification of this jack makes one whale of a difference in the modem's performance. Jack RJ41S is the 8-pin kind with the little switch marked on the side FLL (fixed level loss) and P (programmed.) The pinout of such a jack is: 1 Ring (FLL) 2 Tip (FLL) (pad switched in to Telco in FLL, out from Telco in P) 3 M1 (has something to do with the Exclusion Key 4 Ring (P) (Always connected to Ring of the subscriber loop) 5 Tip (P) (same, but Tip of s.l.) 6) M1C (Exclusion key) 7 PR Programming resistor 8 PC Programming resistor There is a little table on page 99 of part 68 which describes the pad to be used. These resistor values hold for either the FLL pad (for modems with no level programming position inside the modem) or the selection of PR-PC (for modems with this provision). The UDS modem uses the PR-PC resistor when strapped for this operation. PR-PC is selected by the telephone company installer when the line is conditioned for dial-through data and voice service, for (I believe) -9 dBm at the C.O. Around here, they test it at 1001 Hz (?) and the whole thing takes about 1 minute. Jack RJ45S is identical to jack RJ41S except that it brings out fixed (oops, it does NOT bring out) fixed loop loss paddage to pins 1 and 2. We use the UDS modem on dial-through all the time. Internally, it has a jumper for "Permissive" (-9 dBm) for connection to the plain ole RJ11 jack, and "Program" (using the program resistor, it delivers X dB to the C.O.). We have found that it is almost mandatory to specify RJ45S or RJ41S to the phone company whenever compressors are installed. This is because the attack time of a noise-limiting device is slow enough to mangle the training burst from the modem. I have personally installed these modems in three doctors' offices and homes, and many more hospitals. There should be no problem although the tariff that comes with the jack may be more than you want to pay. -dya- .