-=> Quoting Roland Stiner to Dave Garland on PHONE LINES<=-
 RS> Hey, I need help with the basics, what are the yellow and black for
 RS> anyway?  They not connected.
 
 Yellow is ground and black is for AC.. Explanation:  When the princess
 telephone was first introduced way back, the little light bulbs in the
 push buttons required an AC transformer on premises to power them.
 Later versions were powered from the 48 volt telephone network and
 eliminated the transformer.  The ground was used as a return for
 ringing current on party lines.  The green wire is the tip and the red
 wire is the ring.  The names come from their position on telephone jack
 cords of old.  When the operator used to see a light appear on her
 panel, she would plug a cord into your jack and ask you "number
 please."  The cord she used had a solid brass collar which was called
 the sleeve, an insulator, then a ring of metal, called the ring another
 insulator and a tip of metal called the tip.  The telephone operators
 went the way of the dinosaur but the terminology remains today. The
 third wire used only in telephone offices for signaling is still called
 the sleeve. Today most phones are private lines and when the phone
 company sends out a ringing current to ring them, it does it on the
 ring and the power return is the tip.  On party lines ringing curent is
 sent out over either the tip or the ring and returned over the ground,
 and the parties are refered to as the ring party or the tip party. This
 is how they can ring one phone or the other but not both on a two party
 line that shares one cable pair.
 A twisted pair is two wires twisted together, the reason for the
 twisting is to cancel out external interference.  Pairs in a telephone
 cable (ie: 16 pairs or more) are stagger twisted, that is the number of
 twist per pair varies to keep the adjacent pairs from recieving
 crosstalk. Crosstalk is when a person on one pair can hear or be heard
 by a person on another.  If power levels impressed upon the line don't
 exceed FCC mandated levels, then crosstalk does not happen, however if
 a modem or other device is allowed to send its data at a level higher
 than that, others sharing your telephone cable will be interfered with
 and you will be required to remove the interfering device.
 Most home wiring is adequate for the transmission of any speed modem,
 that is unless you have an extremily large home. :)  If your modem is
 line balanced properly and there is no reason to believe that it
 wouldn't be, the telephone network is line balanced at their end for
 the utmost effiency when the line is terminated into a one phone or one
 device terminator.  Hanging things on your telephone line other than
 those designed with the proper line loading can severely effect
 quality.
 The telephone line is designed and tested for voice frequencies falling
 in the range of 400 to 2800 hz.  To send data at speeds greater than
 that, modem makers send approxamatly a 2400 hz signal, this keeps the
 telephone line current reversing itself at an acceptable rate.  The
 data is impressed on that signal as amplitude modulation, almost the
 same as the AM radio broadcast signal.  Problems arise when the data
 rate becomes to fast for the line to adjust between them.  If you
 divide your modem speed by 2400 and divide that result by two, you will
 have the number of bits being impressed on one half cycle of a 2400 hz
 signal. Incidentally FCC rules currently limit the speed of data sent
 to the Telco on a standard dial tone line to 53 kbps.
 Bob..
--- Blue Wave v2.12 [NR]
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