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A recent question about a TP's not breaking the dial tone reminded me that some of you might want to duplicate a little gizmo I built for my own TP to interface it more universally with the phone. BTW- IMHO, the answer to the person's problem with his own TP not breaking the dial tone was that he needed to try PULSE DIALING instead of TONE DIALING to see if it made a difference. Before I start with the description of my own "traveling kit" with breakout box for modem connects, let me give a tiny bit of explanation of the USA phone wiring convention. Most wires to telephones have 2 or 4 conductors. It only takes two of these to make a modem work, so if there are 4 wires, that means there are two POSSIBLE combinations that could work. Think of these as the "inner" and "outer" pair. By convention, these are color coded as RED/GREEN as the inner pair and BLACK/YELLOW as the outer pair. (If you don't believe me, put on your glasses and look very closely at the tiny plug at the end of a phone cord <grin>>. I'm not going to get into a "tip and ring," or "battery and AC" discussion, but want to let you know that the phone circuit isn't like a typical circuit. Its weird. Because of this, and because installers make mistakes, the phone circuit in your office, house or motel room may work fine for telephones, but be a mess for modems. In the USA, we have an electronics chain called Radio Shack, which sells all kinds of telephone gadgetry, in addition to most of the stuff any experimenter would want for any elecrical project One of the things Radio Shack sell is a phone circuit tester, about $5 US. It is a tiny box with a red and green LED on the top and a short cord with RJ11 jack on the end. To work, you merely plug it into a phone jack. If you get a green LED, the "polarity and voltage" are OK. A red LED means that the "polarity" is reversed. No LED means that the line is dead. There's a problem, though. In most phone and modem circuits, only the inner pair of wires (RED/GREEN) run up to a single-line telephone. Should the phone be wired oddly (or wired this way deliberately) you have no way of connecting to the OUTER pair of wires and/or reversing the "polarity" of the circuit. That's where my little box comes in handy. Essentially, my little breakout box does this: I hope my description is adequate for any of you who want to build your own to do so. I may also make up a wiring diagram and put it in my FTP site for anyone to download, but that'll be later on. The box has an "IN" and "OUT" RJ11 female connector. A standard 4-WIRE phone cord connects between the "IN" connector and the wall jack of the phone system. The "OUT" connector on the box uses only an "inner" pair of RED/GREEN and connects with another cord to the TP755's modem port. On the side of the box are three switches. The first switch is a DPDT toggle switch. The incoming four wires connect to the OUTER pairs of poles, with RED and BLACK on the "left" side and GREEN and YELLOW on the "right" side. The center pair of poles are wired with RED on the "left" side and GREEN on the "right" side. As you can see, toggling this switch causes the CENTER poles to alternate between the incoming RED/GREEN pair and the BLACK/YELLOW pair, giving you access to either pair with a flip of the switch, The RED/GREEN leads from the center poles of the first switch pass to a second switch, which is a DPDT also. These connect to ONE END of the DPDT switch: ie the "left and right" poles, and not to the center poles. A second pair of "jumper" wires are connected at the same time to these "left and right" poles and crisscross as they connect to the other poles at the opposite end of the same switch. In otherwords, one end of the "left" side of the DPDT switch is RED and the other end (because of the crossover) would be GREEN. The "right" side would be the opposite. By doing this, when the second switch is toggled, its center poles would be RED/GREEN or GREEN/RED, depending on which end-pair of contacts were being made at the time. In otherwords, the second switch reverses the "polarity" of the wires that has been selected by the first switch. The little tester I bought from Radio Shack "shorts out" the circuit, so it cannot be used at the same time that the modem or phone is actually in use. Therefore, it is necessary to connect it to the center pair of contacts of the second switch via a momentary pushbutton switch. Here a simple SPST Normally OPEN switch will do fine, since having just one wire connected continually means nothing. Therfore, the tester is glued with epoxy to the side of the little box that holds the switches and RJ11 "in" and "out" connectors. Its RED wire is soldered, together with the RED wire running to the RJ11 "out" connector to one side of the center pair of the second switch. Its GREEN lead is soldered to one connector of the SPST Normally OPEN pushbutton switch and another GREEN wire runs from the other pushbutton connection to the other side of the center pair of the second switch. Finally, a GREEN wire from that same center pole of the second switch runs to the GREEN terminal of the RJ11 "out" connector. WHEW! Now in operation, you connect the "in" RJ11 to the telephone cord or to the wall. The "out" is connected to the TP's modem. However, before dialing, you press the momentary button briefly and look to see if you get a green LED. If you do, you have power on whatever pair you're connecte to and the polarity is OK. Toggling switch "one" will cycle beteen the inner and outer pair of wires coming in from the wall, should you have no LED at all. If the LED is RED, toggling switch two reverses the "polarity," giving you a GREEN LED- and therefore a good connection to the modem. Since many of you all in this maillist are engineers or are in science, I hope that I haven't offended you with this little simplistic gizmo. However, there are some of us who are from the business community and need a LOT of guidance in making little gizmos to make our life easier <grin>. I use my breakout box when traveling and can safely tell you that about HALF of the damn hotel rooms I've been in have the "polarity" reversed or use, say, an outer pair of conductors instead of an inner pair. Thomas A. Gauldin Here's to the land of the longleaf pine, Raleigh, NC The summerland where the sun doth shine, BSRB45A on Prodigy Where the weak grow strong and the strong grow great, FAX (919) 676-1404 Here's to Downhome, the Old North State.