[comp.dcom.telecom] Poor Man's Intercom

HGSCHULZ@cs.umass.edu (Henning Schulzrinne) (11/10/89)

By accident I discovered a way to use the phone for in-house calls:
Dial your own number and hang up immediately after the last digit. All
phones in the house will ring and (hopefully) the person you wanted to
talk will pick it up. Is this a special "feature" of our exchange (we
are part of tiny Granby Telephone Company in Western Mass.) or does
that work everywhere?

Henning Schulzrinne  (HGSCHULZ@CS.UMASS.EDU)
Department of Electrical and Computer Engineering
University of Massachusetts at Amherst
Amherst, MA 01003 - USA === phone: (413) 545-3179 (EST); FAX: (413) 545-0724

john@zygot.ati.com (John Higdon) (11/13/89)

In article <telecom-v09i0502m07@vector.dallas.tx.us>, HGSCHULZ@cs.umass.edu
(Henning Schulzrinne) writes:

> By accident I discovered a way to use the phone for in-house calls:
> Dial your own number and hang up immediately after the last digit. All
> phones in the house will ring and (hopefully) the person you wanted to
> talk will pick it up. Is this a special "feature" of our exchange (we
> are part of tiny Granby Telephone Company in Western Mass.) or does
> that work everywhere?

This is something that must be purposely engineered into the CO switch
(it doesn't just happen). It is generally found in "Ma and Pa"
telephone companies (and GTE) due to the high percentage of party
lines in the system. As you might guess, it's used to enable party
line neighbors to call each other.

You dial your party line neighbor's number, hang up, then lift the
receiver when the ringing stops (the switch rings both of you), or if
it appears that there is no answer. This "feature" is generally not
enabled in metro areas, where there are few, if any, party lines. In
fact, Pac*Bell currently has a ring back code that you can subscribe
to (for a monthly charge, of course) so that you can do exactly what
you describe above--have a poor man's intercom.

Given Pac*Bell's money-grubbing tendancies, I'm surprised the
ring-back service isn't timed and measured.

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

wasilko@ames.arc.nasa.gov (Jeff Wasilko) (11/14/89)

In article <telecom-v09i0502m07@vector.dallas.tx.us> HGSCHULZ@cs.umass.edu
(Henning Schulzrinne) writes:

>X-TELECOM-Digest: volume 9, issue 502, message 7 of 11

>By accident I discovered a way to use the phone for in-house calls:
>Dial your own number and hang up immediately after the last digit. All
>phones in the house will ring and (hopefully) the person you wanted to
>talk will pick it up. Is this a special "feature" of our exchange (we
>are part of tiny Granby Telephone Company in Western Mass.) or does
>that work everywhere?

>Henning Schulzrinne  (HGSCHULZ@CS.UMASS.EDU)
>Department of Electrical and Computer Engineering
>University of Massachusetts at Amherst
>Amherst, MA 01003 - USA === phone: (413) 545-3179 (EST); FAX: (413) 545-0724

Out here in Los Angeles, where we are served & abused by GTE (the Great
Telephone Experiment) when I dial my own number I get a series of tones.

When I hang up, the phone rings back and I am greeted by the same series
of tones.

Jeff Wasilko

shri@ccs1.cs.umass.edu (H.Shrikumar{shri@ncst.in}) (11/16/89)

In article <telecom-v09i0502m07@vector.dallas.tx.us> HGSCHULZ@cs.umass.edu
(Henning Schulzrinne) writes:

>X-TELECOM-Digest: volume 9, issue 502, message 7 of 11
>By accident I discovered a way to use the phone for in-house calls:
>Dial your own number and replace the phone ...etc...

Funny, it does not work in Sunderland. (413)-665-XXXX area.

I was very excited when I saw this and tried it at first opportunity.
But it failed. I get the same tones (sort of an engaged tone with a
sore throat :-) each time, just after the number. Irrespective of how
fast or slowly I put back the receiver, the phone never rings back.

(FYI, Sunderland is next door to Amherst, MA, served by the same
phone company. However, the 545 area seems to be a special area for
UMass, so this might be source of the difference in behaviour.)

   shrikumar ( shri@ccs1.cs.umass.edu, shri@ncst.in , (413)-665-7215 )

samho@larry.cs.washington.edu (Sam Ho) (11/16/89)

More on the subject of calling yourself:

Years ago, (back when we had a #5 crossbar) if I dialed my own number,
I'd get a busy signal.  But, if I hung up immediately after dialing,
there would be a ringback.  I suppose we outran the relays opening and
closing.

When we got our ESS, and equal access, I tried again.  Dialing self
gets an immediate busy.  So does 10288-NPA-self.  Using 10777-NPA-self
to Sprint produced silence.  When I hung up, I got ringing.
Currently, no call-self combination I know of produces a ringback on
my phone.  Routing via US West or ATT produces busy.  Forcing MCI or
US Sprint produces silence, or silence follwed by a busy.

Sam Ho

[Moderator's Note: In Chicago, dialing your own number produces one of
two results, depending on the office serving you: Either you get a
busy signal (as I do, regardless of having call-waiting on your line)
or an intercept, 'your call cannot be completed as dialed, please
check the number and dial again'. The offices which render this latter
response to dialing one's own number are using an older generic.

Try calling yourself via your calling card: that is, zero plus the
area code, your number and your pin, terminated with an octothorpe
(#). Here in Chicago, the zero plus gets me out of the local office
and to some other center, thus the return trip from there to here is
delayed by just a couple seconds and I do get a call waiting tone when
the inbound side hits me.   PT]