asterisk users - Feb 2004 - Detecting answer supervison from an AGI app

I've got a dumb Western Electric payphone and some homebuilt hardware to
control the coin relay which is accessible to Asterisk through the AGI
interface. I'd like to be able to set the state of the coin relay to collect
at the end of a call if a called party answers.

[Hey, I admit this project is being persued just for the fun of it ]

Looking through the documentation, there is a way to get channel state, but it
only tells you that the channel is
bridged and does not tell you the called party has answered.

Is there another interface (unix sockets maybe?) which I can
use to query the answer supervison state for a given channel?

Steve.

>I've got a dumb Western Electric payphone and some homebuilt 
>hardware to control the coin relay which is accessible to Asterisk 
>through the AGI interface. I'd like to be able to set the state of 
>the coin relay to collect at the end of a call if a called party 
>answers.
>
>[Hey, I admit this project is being persued just for the fun of it ]
>
>Looking through the documentation, there is a way to get channel 
>state, but it only tells you that the channel is
>bridged and does not tell you the called party has answered.
>
>Is there another interface (unix sockets maybe?) which I can
>use to query the answer supervison state for a given channel?
>
>Steve.
You can use the manager interface.  See the Wiki or various "how-to" 
guides scattered across the four corners of Google.  You'll only be 
able to detect answer supervision with PRI or VoIP calls outbound - 
FXO circuits have no answer supervision.

I'm interested in your payphone application; I was given a payphone 
for the holidays, and I'd like to semi-gut it and put an ATA type 
device in there and an 802.11 adapter.  Feed it 110VAC and point a 
yagi at it from a few miles away.  For that matter, ten or fifteen of 
them.  This is one of those spare-time projects that I've been 
intentionally ignoring, because I'll quickly become distracted with 
trying to build a company that does wireless payphones via IP.  I 
have the business plan mostly written in my head already.  <sigh>

I assume mine generates coin tones; it would be pretty snappy if * 
could detect those tones and do something with them when detected 
in-band in the audio stream.  I don't know how the payphones would 
normally squelch these tones from being replayed into the phones; 
that would be an interesting thing to dig around inside the phone to 
find out about (in my free time!) because I know that playback of 
tones became impossible in the mid 80's due to squelching locally on 
the phones.  I like the novelty of a VoIP phone that collects coins - 
I'm suspicious of this whole "pre-paid" thing.  ;-)

Yet Another Application That Needs Audio Processing After Dial (YAATNAPAD)...

JT

Thanks John,

I'll check the manager interface out. I inderstand FXO interfaces will be
useless for answer supervision.

As for gutting the payphone-- 

You should investigate updating the electronics and make it a smart payphone
which is completely programmable and handles call rating locally. The original
electronics in a WE SS payphone fills up most of the enclosure, but the smart
board will leave you more space.

On the surface, it seems like the smart board programming is a closely held
secret and only dealers have the programming software to make changes. Most of
what I have learned is relevant only to the old dumb payphones which use
1700/2200Hz tones for coin denominations, continuity test between tip and grond
for initial rate, and +/-130V between tip and ground to control the coin relay.

My homebrew interface board is able to check for the presence of the initial
rate in the hopper, and to collect or refund the coins in the hopper. The
interface board has an RS-485 connection to the Asterisk box so that an AGI can
test and control the payphone operation.

BTW: The reason you could not simulate the tones on a payphone after the early
80's is because the phone had
a notch filter which could be inserted in the microphone
path when the tip and ring polarity was reversed. The automated coin telephone
system, and the operators reversed
the polarity on the line when coins were about to be deposited.

Steve.





> 
> From: John Todd <jtodd@loligo.com>
> Date: 2004/02/03 Tue PM 11:15:59 EST
> To: asterisk-users@lists.digium.com
> Subject: Re: [Asterisk-Users] Detecting answer supervison from an AGI app
> 
> >I've got a dumb Western Electric payphone and some homebuilt 
> >hardware to control the coin relay which is accessible to Asterisk 
> >through the AGI interface. I'd like to be able to set the state of 
> >the coin relay to collect at the end of a call if a called party 
> >answers.
> >
> >[Hey, I admit this project is being persued just for the fun of it ]
> >
> >Looking through the documentation, there is a way to get channel 
> >state, but it only tells you that the channel is
> >bridged and does not tell you the called party has answered.
> >
> >Is there another interface (unix sockets maybe?) which I can
> >use to query the answer supervison state for a given channel?
> >
> >Steve.
> 
> You can use the manager interface.  See the Wiki or various
"how-to"
> guides scattered across the four corners of Google.  You'll only be 
> able to detect answer supervision with PRI or VoIP calls outbound - 
> FXO circuits have no answer supervision.
> 
> I'm interested in your payphone application; I was given a payphone 
> for the holidays, and I'd like to semi-gut it and put an ATA type 
> device in there and an 802.11 adapter.  Feed it 110VAC and point a 
> yagi at it from a few miles away.  For that matter, ten or fifteen of 
> them.  This is one of those spare-time projects that I've been 
> intentionally ignoring, because I'll quickly become distracted with 
> trying to build a company that does wireless payphones via IP.  I 
> have the business plan mostly written in my head already.  <sigh>
> 
> I assume mine generates coin tones; it would be pretty snappy if * 
> could detect those tones and do something with them when detected 
> in-band in the audio stream.  I don't know how the payphones would 
> normally squelch these tones from being replayed into the phones; 
> that would be an interesting thing to dig around inside the phone to 
> find out about (in my free time!) because I know that playback of 
> tones became impossible in the mid 80's due to squelching locally on 
> the phones.  I like the novelty of a VoIP phone that collects coins - 
> I'm suspicious of this whole "pre-paid" thing.  ;-)
> 
> Yet Another Application That Needs Audio Processing After Dial
(YAATNAPAD)...
> 
> JT
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