I've just finished the O-Reilly book on Asterisk and setup a separate computer with Asterisk@Home. The book has a lot of good information but for some reason does not discuss the physical wiring that goes to stations (FXS) and FXOs. I understand that cat5 type wire would be used. What commonly used standards, if any, are used on the various colored wires? What signals and voltages to they carry? Presently I have a lot of POTS telephones all wired in 'home run' with a single cat5 from line 1 of a station RJ-11 station block to type 66 blocks where the Asterisk equipment will live. Can I do the same with Asterisk station lines - that is each extension would be a single pair or two from Asterisk that carries power, ringing current and voice. What equipment do I need at the Asterisk end to connect multiple analog POTS phone each station? I also need to know how many wire pairs are needed for non-POTS phones and what those wire carry. If feasable the easiest wiring method is to end up with all POTS phones on the default inner pair line 1 (blue) and non-POTS phones on line 2 (orange) and if necessary, 3 (green) leaving 4 (extra pair possibly used for direct connection to CO line for emergencies). That way any single (not double) line POTS phone can be safely plugged in as they are all on line 1. Could this be done? My mnemonic for telephone wire color coding is "BOG Brown". I'm interested in any comments on physical wiring. Larry -- Larry Alkoff N2LA - Austin TX Using Thunderbird on Slackware Linux
trixter aka Bret McDanel
2005-Oct-21 13:49 UTC
[Asterisk-Users] How to wire Asterisk to stations?
On Fri, 2005-10-21 at 15:39 -0500, Larry Alkoff wrote:> I've just finished the O-Reilly book on Asterisk and setup a separate > computer with Asterisk@Home. > > The book has a lot of good information but for some reason does not > discuss the physical wiring that goes to stations (FXS) and FXOs. > > I understand that cat5 type wire would be used. > What commonly used standards, if any, are used on the various colored > wires? What signals and voltages to they carry?This is tough to answer becuase it varies based on country. I will assume that you are in America and give you that info ... A pots line uses 2 wires. Ring and tip (designations from back when they were plugs, like a headphone plug). Ring is negative voltage and tip is positive. Tip is switched, the reason they switch the positive voltage side is to prevent corrosion on the poles. When the phone is onhook (hung up) ring has -48VDC normally. When you pick up the phone (offhook) its about 7vdc. When the phone rings its 90-110vac @ 20Hz. The reason it goes AC for ring is due to the old mechanical bells that were in use way back when. This would cause the electromagnet to fire then release which causes the hammer to strike the bell and make noise. Now that everything is more sophisticated this backwards compatibility has to be preserved. As for wiring, when using regular phone wire (internal) it will usually be 2 pair to be connected to a RJ-11 or RJ-12 connector. Red is the primary ring, green primary tip. Yellow and black are used for the 2nd line. The reality is that it doesnt matter what color goes where, inductance is usually not a problem for analog lines so twisting often doesnt occur in phone lines. Just make sure that you get it the same on both ends (which largely doesnt matter as much anymore either, but with some equipment it still does). On a RJ-11 or RJ-12 connector it will be the center two for the line. Any other wires are only used if its a dualline device. When it comes to FXO/FXS stuff normally they are single line ports so you only need 1 pair per connection. -- Trixter http://www.0xdecafbad.com Bret McDanel UK +44 870 340 4605 Germany +49 801 777 555 3402 US +1 360 207 0479 or +1 516 687 5200 FreeWorldDialup: 635378 -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 189 bytes Desc: This is a digitally signed message part Url : http://lists.digium.com/pipermail/asterisk-users/attachments/20051021/5f7b8eed/attachment.pgp