PHONE.TIP

Converting Telco 50-pin Multiline to 2-lines-in-one cable RJ14 Modular Jacks
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Adaptors appear not to be available for this logical conversion; the 4-line Radio Shack adaptors convert to four RJ11 jacks, and then one must buy Y-splits with long cables to merge 2 RJ11 lines into an RJ14 2-lines-in-one-cable arrangement.  The result is messy and unduly expensive; having spent an afternoon figuring out RJ14s, here goes.

Two nonparty phone lines are accommodated within one standard four-wire modular phone cable:  the two center wires, red and green, are the standard line, and the two outside wires, yellow and black, are used for the red-green of the second line.

The Amphenol 50-wire connector uses pins 1 and 2 for red-green of line 1, and pins 7 and 8 for red-green of line 2.  A simple conversion is to buy a one-line Radio Shack adaptor (the kind used to tap into Line 1 of a multiline office phone, sandwiched between the usual connectors), which has yellow-black for Line 1 wired to Amphenol pins 3 and 4 in the usual RJ11 manner.  Cut these, and tap into the white-black pair through-put wires for pins 7 and 8 (that's Line 2; Line 3 is pins 13-14, Line 4 is 19-20; just count down from the existing red-green on 1-2).  This will make the usual modular jack into a proper RJ14 two-lines-in-one-cable arrangement.  Or, if you can find an Amphenol 50-pin plug, just wire up an RJ11 to pins 1,2,7,8.

Once operating out of an RJ14 equivalent jack, standard one-line cables and splitters may be used to accommodate two-line traffic; no special cabling is needed thereafter, so long as the 2-line phone has an RJ14 jack (usually labeled L1/L2).  If you want single-line answering machines, modems, etc., on one or another of the lines, Radio Shack for $7 sells a small 3-jack splitter with L1/L2 in and out, plus L1-only and L2-only output jacks.  While line 1 is indeed still on the center red-green pair, single-line phones or modems may ground the flanking black-yellow pair and thus interfere with Line 2 operation elsewhere; that's why the $7 splitter is usually needed.  If you have a two-line phone with a second modular jack labeled L2 only, you can probably plug your answering machine or modem into it for tapping into Line 2 without interference with Line 1.

			W.H. Calvin