An ISP of their own (was RE: [rescue] Being jobless)

Sandwich Maker adh at
Wed Jul 30 14:48:10 CDT 2003

"From: Stephen Sandau <ssandau at>
"> >>> The old T1 in the last building just arrived as 4 copper wires from 
"> >>> the demark just like the phone lines. Dunno what "format" that was, 
"> >>> but there was no internal electronics at all..
"> >> That would be HDSL.  1.5 megabits over two pairs, 2 megabits over 3
"> >> pairs, maximum range about 20,000 feet.
"> >
"> > I thought it was not, since the HDSL we have requires a box on the 
"> > wall in our office. the old setup had 4 copper wires that came in off 
"> > the pole and went right into a CSU/DSU.
">    It's not.  HSDL didn't exist in 1972, and T1s sure did.  T1/DS1 is a 
"> baseband digital protocol that runs relatively high voltages (compared 
"> to POTS lines) over bare copper.
"Now that I think about it further, I believe that the old 4-wire data circuit 
"in the old building was only a 56K connection. It was installed in the early 
"90's I think. That would also explain the part about it plugging into a CSU/DSU 
"instead of a TSU...
"The higher-voltage thing may have been how the 56K workd as well...

afaik t1/ds1 does not use high voltages relative to pots; a 20ma
current loop can have over 100v on it, and the ringer!  afaik t1
lines are +/- 5v.  iirc 56k ds0 lines are the same.

i worked with t1 gear for seven years at att-bl.  okay, it was the
test and integration lab, but i started there as a tech.

and it's always called a csu/dsu regardless of the speed of the line
it's terminating.

and speaking of tarriffs - while i was there, they replaced the four
existing t1s that tied us to the rest of the submarine with four new
lines.  why?  we were paying $1200/mo each for the old lines and the
tarriff on new was $800/mo - but they couldn't change the rate on
existing lines...
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen
adh at                       and think what none thought

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