[comp.dcom.telecom] Unanswered Trunk Enhancement

slr@tybalt.caltech.edu (Steve Rhoades) (12/04/90)

In article <15088@accuvax.nwu.edu> John Higdon <john@bovine.ati.com>
writes:

>Pac*Bell Weenie Note: In the Pac*Bell implementations of the 1AESS
>(W.E.  should never have provided them with the source!), you would
>still get busy, even when dialing through Telecom*USA. PB's generic
>will not allow CW or 3W until the first call is supervised. Pac*Bell
>had some lame reason for doing this, but I forgot what it was.

I believe it's called Unanswered Trunk Enhancement.  As you know, it
was phased into all of Pac*Bell's generics a few years ago.

Their logic for doing this: 

When a person with three-way calling dialed a number which was busy,
the calling person would flash momentarily, then retry the call.  The
problem was the person wouldn't get a "new" dialtone but a three-way
dialtone.  No problem if the number being called was still busy - both
connections would disconnect when the calling party hangs up.  But, if
the call attempt made with the three-way dialtone was successful
(person being called answered and a long conversation ensued) the busy
signal would still be on hold tying up Pac*Bell's precious resources.
We know what THAT can lead to :-).


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