Re: phone tones and Keith Doxey's help?

[Adrian <yahoo1@xxxxxxxxxxxxxx>]

Keith

further news, I am on a BT line, spoke to them today, they said i was on
a system Y exchange and the disconnect clear time is hard set and cant
be changed (apparently 100ms). So I guess if its on and it worked on on
my comfort I, is it possible something has changed and I have too much
interference on the line and comfort II isnt detecting the break?

Adrian



Keith Doxey wrote:
> I concur that it is NU tone.
>
> Exchanges now give the called subscriber Number Unobtainable Tone (NU
Tone)
> if the incoming caller clears and the handset is not replaced. This
> disappears after a period of time to be replaced by the
"howler" which is a
> two tone noise that increases in volume to alert someone to the
handset not
> being replaced properly.
>
> Description of tones can be found here
> http://www-users.cs.york.ac.uk/~fisher/telecom/tones/
>
> As it is actually 10 years since I worked on phone lines I cant be
sure of
> the exact conditions that are now present on phone lines but
imeadiately on
> termination of a call there was a momentary break in the line known as
the
> "K break". (Name derived from the relays used in early
strowger exchanges.
> Each line had dedicated LR & K relays but shared the other
exchange
> equipment with many other lines)
>
> Answering machines detect this condition and stop recording. I had an
> answering machine that worked perfectly on an exchange line but when
used on
> an extension on my Pentara it used to record continuously as it didnt
see
> the line break.
>
> Out of interest... is this a BT line or some other provider ?
>
> ***
> >From http://www.dt4u.com/dtsystems/dialupfaqnew.php
>
> "Why will my Dialup not Clear down when I hang up (Auto Mode)
>
> Some exchanges notably NTL have a non standard cleardown sequence
where the
> industry standard K break signal is missing. The only work around for
this
> problem is to switch off your Dialup unit at the conclusion of the
program.
> If you wire up the mains as shown elsewhere, this will happen
> automatically - whenever the sound system is switched off."
> ***
>
> Whilst Googling for info on the "K-Break" I came across
this....
>
> http://www.ukha-archive.com/ml/ukhad/2001-mar/msg00924.html
>
> ... written by some bloke called Keith Doxey, whoever he may be!
>
> ***
> "It could be the exchange.
>
> There is a period of time called the "Disconnect Clear Time"
when the
> exchange line is physically removed to allow equipment to fully
disconnect
> from the call. This is the modern digital equivalent of what used to
be
> known as the "K Break" on strowger exchanges. Many answering
machines used
> to make use of this to stop recording if the caller hung up.
>
> Some exchanges have this disabled as some modern PBX's interpret the
> reconnection of power to the line as a new incoming call and will
start a
> phantom ring that stops after a couple of seconds.
>
> Just another useless bit of trivia for you :-)
>
> If it is causing you real problems you could try calling faults and
getting
> the disconnect Clear Time set to Zero."
> ***
>
> Which has just kicked the old grey matter into gear again. It could be
that
> if you do have a BT line, it might have been set to have Zero or
> insuficiently long "Disconnect Clear Time" for the Comfort
to release. Might
> be worth asking Comfort Tech Support if there are different specs for
the
> Disconnect clear on Comfort 2.
>
> HTH
>
> Keith
>
>
>
>
>> -----Original Message-----
>> From: Kevin Hawkins [mailto:lists@xxxxxxx]
>>
>> I'm sure it's got a proper name but from memory it sounds the same
as
>> the NU  number unobtainable tone at 400Hz I believe - could be
>> wrong though
>>
>> K
>>
>> Adrian wrote:
>>
>>> Hi
>>>
>>> thought Keith would be the man for this but maybe someone else
has the
>>> knowledge.
>>>
>>> short story, after upgrading from comfort 1 alarm system to
comfort 2
>>> (yes, you may have seen this on the comfort tech site but are
after more
>>> tech detail to help solve this issue), when people leave a
message on
>>> comfort 2's answerphone, it doesnt detect they have hang up
and records
>>> a continuous tone (comfort 1 never had a problem with this)
>>>
>>> so whats this tone called (sounds like dialtone but higher
pitched) and
>>> what frequency is it at? any weblinks that might explain this?
>>>
>>> thanks in advance
>>>
>>> Adrian
>>>
>>>