5294 controllers on 56k lines

Dear Midrange-L:
A word of warning to those of you attempting to use IBM 5294 WS
controllers on 56k digital lines: be prepared to spend a few hundred
bucks extra for DSU's.  We didn't; and after two nightmarish weeks
involving not only the phone company and DSU manufacturer techies but
also two high powered gurus with a protocol analyzer, we figured out the
problem.  The 5294 controller's interface is prone to intermittent
fluctuating voltage levels which do not affect slow speed modems but
cause random, unexpected line degradation and failure in the low-end
(=cheap, <$350) DSU's recommended by the phone company.  Replacement of
these DSU's with more flexible (=expensive, >$750) units seems to have
solved the problem (as spending money often does <g>).  To TELCO's
credit, they did pay for part of the replacement cost ...
HTH,
Willy 

----------------
  Willy Wilson                  
willy@riback.com           
Columbia, MO USA
----------------

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