How do you say "Recall" to a telephone?

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I am writing a program that outputs DTMF tones from my computer
speakers to dial telephone numbers in my address book. I decided to
add a button to do automatic call back if the number is engaged. The
instructions in the phone book which are also here -
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say to press "Recall" then *37#. Can I send tones to emulate "Recall"
or is it some other change of state on the phone line? If the latter,
what is it?

Re: How do you say "Recall" to a telephone?


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Not that I know of. When you press redial on any phone I've tried, the
controller in the phone drops the line, picks it back up again, then
plays back the last dial sequence. Ie. hang up and try again.

Cheers,
Nicholas Sherlock

Re: How do you say "Recall" to a telephone?


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Wouldn't it be easier just to send the number again?

Cheers.

Ken



Re: How do you say "Recall" to a telephone?



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That would be fine but it does not seem to work. I have tried sending
the number followed by *37# in response to the engaged tone. I have
also tried some variants involving one second pauses but all I get is
the engaged tone. Is there some way of sending the number that you
believe will work?


Re: How do you say "Recall" to a telephone?




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If you are getting busy tone, then you *must* hang up. Dialling anything
else without hanging first is just pointless. Try it manually. The
Recall code (*37#) is only a command that indicates that something else
is to follow, it certainly is not the equivalent of hanging up & letting
the line reset.

Kevin Martin

Re: How do you say "Recall" to a telephone?



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I think you are right but I was responding to a post that proposed
sending the number again. "Hanging up first" does not solve my problem
because sending the original number after hanging up, not
surprisingly, results in the engaged signal again.
 
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I don't understand this bit. *37# does not expect anything else to
follow. Trying it manually indicates that if it is preceded by Recall
(Flash) it results in the Call Back behaviour I am seeking.
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Re: How do you say "Recall" to a telephone?


["Followup-To:" header set to aus.electronics.]

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so when the busy tone is detected you need to flash the hook (send the
recall pulse) and then send the tones, to flash the hook all other
devices on that line must be on hook. or the CO will only see a click.

how are you controlling the phone line?

--

Bye.
   Jasen

Re: How do you say "Recall" to a telephone?



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"Controlling" is a bit of an overstatement. Franc Zabkar remembered
the modems of our youth and recalled the technical term. So I will say
that I am using an acoustic coupler. Here's my original post-

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Thanks to several posts I now understand what Recall (Flash) does at
the exchange. For the time being I have accepted that I cannot
acoustically couple a Recall/Flash but I still would liked to send the
appropriate sequence of tones after the Flash to enable automatic call
back. I have, so far, failed. The Flash is not the problem since
automatic call back works if I use the phone to key in the *37# and
press dial.

Re: How do you say "Recall" to a telephone?


[...]
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Yes, but you are hanging up with the phone then picking up again before
dialling, aren't you? This is what the flash *is*.

Cheers,
Nicholas Sherlock

Re: How do you say "Recall" to a telephone?


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Whoops, misread you the first time. Recall is dropping the line for some
small amount of time (<1 second) and picking it back up again as a
signal to the phone company. You cannot emulate it with tones.

Cheers,
Nicholas Sherlock

Re: How do you say "Recall" to a telephone?



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Nope.


Yes, its a timed line break.

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Its a lot simpler to just dial the number
again when you have the dialing automated.



Re: How do you say "Recall" to a telephone?


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You need to be able to release and grab the line, you cannot do it with
audio...


Re: How do you say "Recall" to a telephone?


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I think from memory that ATD@ is a hookflash command but then you're hoping
that the modem correctly implements it and that it suits the line that's
being used. It would be more reliable to dial again.

Cheers.

Ken



Re: How do you say "Recall" to a telephone?


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And yes, I went off on a tangent and he's using audio not a modem. Tea time,
old chap.......

Ken



Re: How do you say "Recall" to a telephone?


finger to keyboard and composed:

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LOL. An acoustic coupler.

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Why not use a modem and a built-in app? Windows 98, for example, has
an app called "dialer.exe". You use the dialer to make the call and
then hang up the modem after picking up your parallel connected
telephone handset.

If you prefer to write your own app, then send commands such as ...

 AT DT nnnnnnnn;

or ...

 AT DT !*37#;

In the case of my Rockwell modem, the "!" flashes the switch hook for
a period of time defined by S-register S29.

For example, AT S2970% sets the hookflash duration to 700msec.

Listen for modem responses such as "BUSY", "NO DIALTONE", "VCON", etc.

The ATH and ATH1 commands cause the modem to go on-hook and off-hook,
respectively.

If you have a "hardware" modem, then you could probably automate the
dialing procedure using a simple DOS batch file.

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

Re: How do you say "Recall" to a telephone?



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It's the usual hardware/software trade off. My study has two telephone
lines and only one modem. My wife's study has no telephone lines and
no modem but she does have a cordless phone. :)

Re: How do you say "Recall" to a telephone?


Sorry about oversimplistic response to first post.  Lots of good sense here and
I was way too shallow.


Re: How do you say "Recall" to a telephone?



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The 'recall' function is commonly referred to as 'hook flash' where the line
is dropped and picked up within a short period of time. There probably is a
way to send some sort of command to the exchange hardware that tells it you
want to initiate the same function as if you've flashed the line, but
Telstra probably would do their utmost to make sure nobody can find out
about it. 8-)

Craig.
--
 SUN RIPENED KERNELS - Surplus Sun Microsystems Equipment, Parts + Accessories
    Waterfall, NSW, Australia - Operated by Craig Dewick - Founded in 1996
We've slightly trimmed the long signature. Click to see the full one.
Re: How do you say "Recall" to a telephone?


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"recall" is another name for a hook-flash (a rapiid onhook-offhook)

that's done with a '!' in the dial-string if your modem supports it.

 atdt !*37#
 
Bye.
   Jasen

Re: How do you say "Recall" to a telephone?


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I believe there are two standards for the duration of the
hook-flash, and the Australian one is between 100-500ms.
The other system is under 100ms, which was all that was
supported on one old (non-approved) phone we bought. I
used to simply bump the hang-up button instead, until we
replaced it with a legal phone.

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