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barrett@opera.iinet.net.au (Barrett Communications) wrote:
>I am looking for means of determining if a person has picked answered a
>phone (normal analogue).  
>
>As far as I know there are three means for
>determining if the phone has been answered.  The first two I have covered,
>the last I no nothing about.  
>
>


[snip]
  
>
>3) Line Reversal?  There is meant to be a
>polarity change on the tip and ring inputs as soon as the phone is picked
>up?  Does anyone know anything about this and/or how to measure it?  Also
>may not be available in all countries?  
>
>Any help appreciated,
>
>Damian


Try having a look in the old in BS6450:Part 1 spec.

I believe it used to talk about (I may be wrong !) 
something yo do with an answer signal returned 
from the exchange, so that a
PBX knew that the outgoing call had been answered. Is this the
sort of thing you are looking for ? Or do you want to
know if an incoming call was answered succesfully
before the caller gave up and hung up ?

If the latter is true, I would be interested in hearing
a way of doing it, if you find you are successful.

Simon Watkins        email simon_watkins@nt.com

Simon Watkins <simon_watkins@nt.com> writes:

>barrett@opera.iinet.net.au (Barrett Communications) wrote:
>>I am looking for means of determining if a person has picked answered a
>>phone (normal analogue).  

In the US, this is termed "supervision"...

There is no reliable supervision back to the originating
line, with one exception.

In some locales, CPC [a momentary drop in loop current is
offered up on disconnection. But depending on it is a bad idea.

The exception is ISDN. It does provide full supervision.


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& no one will talk to a host that's close...........(v)301 56 LINUX
Unless the host (that isn't close).........................pob 1433
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In article <wb8fozDw6tDt.BLF@netcom.com>,
David Lesher <wb8foz@netcom.com> wrote:
>Simon Watkins <simon_watkins@nt.com> writes:
>
>>barrett@opera.iinet.net.au (Barrett Communications) wrote:
>>>I am looking for means of determining if a person has picked answered a
>>>phone (normal analogue).  

   I assume you want to detect answer from a different calling telephone,
not by monitoring the called line....

>In the US, this is termed "supervision"...
>
>There is no reliable supervision back to the originating
>line, with one exception.
>
>In some locales, CPC [a momentary drop in loop current is
>offered up on disconnection. But depending on it is a bad idea.
>
>The exception is ISDN. It does provide full supervision.

   I think ISDN is ideal (and fast) for this application.  But there is
another standard method available ONLY on analog 2-wire lines.  The feature
is called "Answer Supervision - Line Side" by some TELCos; we called it
"Calling Line-Side Supervision" on the 5ESS-2000 switch.  The interface is
simple - Tip/Ring battery & ground are reversed when the called party goes
off-hook and reversed again when the called party goes on-hook.  The line
is restricted to virtually NO features, and may not be compatible with
some out-side plant equipment (pair-gain devices).  It's also unlikely
to be tariffed as a residential feature, and only available on selected
switches....

Al Varney - just my opinion

In article <4urbmp$7el@opera.iinet.net.au>, Barrett Communications
<barrett@opera.iinet.net.au> writes
>I am looking for means of determining if a person has picked answered a
>phone (normal analogue).  
>
TOTAL SNIP
It may not be of much help but - when you use Hg on indirect, you get a
tone signal on answer.  I have used this successfully to get credits
from them when I have heard the beep - but no connection.  Subsequent
checking of account proved I was billed.

This tone can be supressed on request and might (?) be available on
direct connect calls.

In the early days of my relationship with the lady with whom I now share
my life - she knew it was me calling because none of her other friends
used Hg.  For some time I was called 'Beep'.  (Just a diversion, it must
be the silly season and the temperature tomorrow is going to be well
into the 70s!)

Voice Systems Specialist 
Simon C. Allen
+44 (0)1442 842702

 
Im Artikel <4urbmp$7el@opera.iinet.net.au>, Barrett Communications (barrett@opera.iinet.net.au) schreibt
>I am looking for means of determining if a person has picked answered a
>phone (normal analogue).  


>3) Line Reversal?  There is meant to be a
>polarity change on the tip and ring inputs as soon as the phone is picked
>up?  Does anyone know anything about this and/or how to measure it?  Also
>may not be available in all countries?  

I understand this was (is?) only applied to local call metering; LD is always
12 or 16 kHz. Anyway, if you experience polarity change you are in a local
net where polarity change meters are availlable from your telco or at a phone 
shop. Just tap the circuit of the meter, e.g. the coil of the electromechanical 
display.

Kind regards,   Volkmar

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