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From: dplatt@coherent.com (Dave Platt)
Newsgroups: comp.dcom.telecom
Subject: Re: Wrong Numbers With Nobody Talking
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Date: 22 Sep 89 19:04:07 GMT
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X-TELECOM-Digest: volume 9, issue 405, message 3 of 5

In article  you write:
>
> I moved a couple of months back, and I've had a weird problem since then.  I
> get lots of wrong numbers.  Some of them are the normal "Is Joe there?" and
> I say no and the person goes away.  But the vast majority of them have no
> voice at all.  I pick up the phone, hear a faint 'clickclickclick' in the
> background, and nothing happens, so I hang up.  On my answering machine,
> I don't get any message either; just those faint sounds.  I thought perhaps
> it was people calling me from a computer, but then I'd hear a modem tone,
> wouldn't I? ...

No, you would very probably not hear a modem tone, if a modem were
dialing you.

With most modems in use today, the _answering_ modem is responsible for
sending the first tone, after it goes off-hook.  The type of answer-tone
transmitted identifies the protocol(s) that the answering modem is able
to use.  The originating modem "hears" the answer tone, chooses a protocol,
and begins transmitting its carrier.  The answering modem "hears" the
originator's carrier, stops sending the answer-tone, and begins
transmitting its carrier.  If, on the other hand, the originating modem
never "hears" an answer tone, it will never "know" that the call has
been answered, and will simply disconnect after 30 seconds or a minute
and report a "NO CARRIER" situation to its pilot.

So, a local- or long-distance call with nothing but silence on the other
end could very well be from a modem.  There are a couple of relatively
common ways that you can end up with numerous calls of this type:

1) Somebody at a specific computer site has misprogrammed one of their
   outdial modems... for example, transposing a digit in the
   phone-number used to contact one of their "neighbor" systems.  If
   this has occurred, most of all of the calls you receive will be from
   the same exchange (either all local, or all long-distance), and
   there's a fairly good chance that they'll stop after a few weeks.
   The sysadmin of the offending system will (probably) notice that a
   large number of calls aren't getting through, will figure out the
   problem, and will correct his/her dialer-file.

2) The phone numbers for computer-hobbyist "bulletin board" systems tend
   to be passed around between personal-computer users.  Bulletin-board
   systems tend to come and go fairly frequently... the survival time
   for a BBS tends to be measured in months.


   If the phone number for a BBS is circulated widely, then there may be
   literally thousands of people who have a copy of the number.  If that
   BBS then goes out of service (for example, if its owner/sysop moves),
   then the phone number will often be given out to someone who is
   having phone service installed.  Subsequently, the new "owner" of
   this number will receive many, MANY phone-calls from computer
   hobbyists who aren't aware that the BBS is out of service.

I rather suspect that you're facing the second of these situations,
since you seem to be receiving calls from both local and long-distance
sources.  The only really effective solution of which I'm aware is to
ask the phone company to give you a different phone number.  They'll
probably charge you for the service-change, since they can legitimately
argue that the problem is not _their_ fault.

Dave Platt    FIDONET:  Dave Platt on 1:204/444        VOICE: (415) 493-8805
  UUCP: ...!{ames,sun,uunet}!coherent!dplatt     DOMAIN: dplatt@coherent.com
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  USNAIL: Coherent Thought Inc.  3350 West Bayshore #205  Palo Alto CA 94303

[Moderator's Note: Some telcos, like Illinois Bell, will change a
subscriber's number once for free, if the subscriber complains of
receiving nuisance or obscene calls. The original correspondent's
complaint would probably fit in this category.  PT]