JTUCKER@vax2.cstp.umkc.edu (12/01/90)
Question: Once in a while when I call a number that is busy several times in a row I get another dial tone. Sometimes someone else picks up the line and tells me to get off. Can someone tell me what is happening here??? Joseph Tucker JTUCKER@UMKCVAX2 [Moderator's Note: Is your service coming from some old, ancient stepper switch or similar? When I was on one of those many years ago it was not unheard of to get conditions like you mention sometimes. PAT]
john@bovine.ati.com (John Higdon) (12/03/90)
JTUCKER@vax2.cstp.umkc.edu writes: > Question: Once in a while when I call a number that is busy several > times in a row I get another dial tone. Sometimes someone else picks > up the line and tells me to get off. > [Moderator's Note: Is your service coming from some old, ancient > stepper switch or similar? Crossbar is particularly vulnerable to this type of problem. It is known as "double connection" and is briefly mentioned in the service manuals and in some Bellcore publications. If you compare a crossbar system to mechanical computer, it is easy to see how this can happen. The "CPU" is the marker, whose job it is to allocate resources and connect them at the proper time. Being a mechanical device (a bunch of relays) and working with registers, trunk units, etc. that are also mechanical, it can become confused regarding the availability of a particular line or trunk unit and seize two at once. Dialing a number can simultaneously produce a busy signal and dial tone, or more likely, a busy and RBT which may eventually be answered and may or may not be the party you were calling, etc., etc. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@bovine.ati.com | San Jose, CA 95150 | M o o !