[comp.dcom.telecom] Answering Machine "Calls Back?"

rang@cs.wisc.edu (Anton Rang) (12/13/89)

My officemates and I have noticed a curious phenomenon when we call
our answering machines from the office to check if we have messages.
After we hang up, our office phone (which we just called from) often
starts ringing almost immediately.  When we pick it up, all we hear is
the hangup "click".

  What causes this?  Please respond by E-mail to rang@cs.wisc.edu, as
I don't always have time to read this group.

	Thanks in advance!

	  Anton

[Moderator's Note: But please copy the Digest with your replies.  PT]

john@bovine.ati.com (John Higdon) (12/15/89)

Anton Rang <rang@cs.wisc.edu> writes:
> My officemates and I have noticed a curious phenomenon when we call
> our answering machines from the office to check if we have messages.
> After we hang up, our office phone (which we just called from) often
> starts ringing almost immediately.  When we pick it up, all we hear is
> the hangup "click".

You have left out a considerable amount of information, such as: 

1. Are you using single-line phones behind a PBX or proprietary phones?

2. What, if any, calls did you make immediately preceeding your call
the the answering machine? 

3. If single-line, what type (flash, standard, etc.)?

When I sold PBXs, before we started using "flash" phones (phones that
have a timed hookswitch "flash" for feature activation and a timed
disconnect to prevent an inadvertant flash) we had a lot of customers
complain of similar occurances. It goes like this:

You make a call on the single line phone. It's busy, or doesn't
answer, or you are otherwise in a hurry to check your machine. You
hang up on the previous call for the length of time of a "flash",
putting the first call on hold. You get (second) dialtone, dial "9",
then dial your call. In the meantime, the hold timer has determined
that your previous call has been on hold long enough, but can't do
anything about it. Then you hang up on your answering machine. The
switch now sees your idle line and rings you (hold callback) to remind
you that you left a call on hold. When you answer, you get what ever
junk was left from that first call. Maybe a busy, ringback, or just
clicks.


        John Higdon         |   P. O. Box 7648   |   +1 408 723 1395
    john@bovine.ati.com     | San Jose, CA 95150 |       M o o !

rang@cs.wisc.edu (Anton Rang) (12/16/89)

John Higdon <john@bovine.ati.com> writes:

>I said:
>> [ When I call my answering machine from the office, my office phone
>>   rings after I hang up. ]

>You have left out a considerable amount of information [ ... ]

  We have standard single-line phones, running through a Centrex
system (don't know any details about that, except that it's activated
by special dialing sequences and/or using a "flash").  This happens
whether or not we've made other calls recently.

> [ PBX possibility deleted ]

  This isn't what's causing our problems, as far as I can tell -- we're
not making any other calls before this....

  Thanks for your help!

		Anton (rang@cs.wisc.edu)