How does a telephone handset work?

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I want to rig up my computer to be a tty/tdd set for the hearing impaired. I found this software.

http://www.dxsoft.com/en/products/calltty

I'm trying to avoid building the circuit.

I was thinking of using of these instead.

https://www.ebay.com/itm/CallTel-RJ9-Jack-to-3-5mm-Dual-Plugs-PC-Card-Y-Training-Adapter-Cord-2-MUTE-Keys/261885051425?hash=item3cf990c221:g:8LQAAOSwPhdVUZfI

These things are designed to connect handsets to the sound card, but I want to connect the sound card to the handset connector on the phone. Does that work? How does the handset communicate with phone?  

Re: How does a telephone handset work?

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https://en.wikipedia.org/wiki/Modular_connector#Handset_wiring

Thank you,

--
Don Kuenz, KB7RPU

Re: How does a telephone handset work?
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If you want to be legal, don't. use a voice-capable modem with
apropriate sound drivers. Or use accoustic coupling, tape a speaker to
phone's microphone and an microphone to the phone's speaker.

If you don't think you'll get caught. use isolating transformers in
place of the speaker and microphone of the receiver and connect them
to line-in and line-out on the sound card, you may need to add
resistors to reduce the volume levels.

https://en.wikipedia.org/wiki/Modular_connector#4P4C

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This email has not been checked by half-arsed antivirus software  

Re: How does a telephone handset work?
On Friday, December 22, 2017 at 3:33:24 PM UTC-5, Jasen Betts wrote:

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That's what I'm going to try to do. I going to just build a cradle for the handset and go the microphone connected to the speaker route.

I can't believe these overpriced TTY/TDD devices. They look like 1970's teletype machines with an old fashion modem and a calculator display. I want a card I can plug into my computer.

Re: How does a telephone handset work?
Wanderer wrote on 12/22/2017 4:49 PM:
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Is there a reason why you don't just connect a standard modem to your  
computer?  My understanding is they often support both voice and data  
operations.  Why do you need to reinvent the wheel?  I just saw a 56 kbps  
modem on ebay for $30 plus shipping.  Plug it into the wall, plug it into  
your computer and you are good to go, no?

--  

Rick C

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Re: How does a telephone handset work?
On Friday, December 22, 2017 at 6:49:16 PM UTC-5, rickman wrote:
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I've asked the same question but I can't find any tty/tdd software to work over a voice modem and I don't understand why.

Re: How does a telephone handset work?
Wanderer wrote on 12/22/2017 7:37 PM:
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That seems crazy.  Maybe they don't realize it doesn't need to be different?  
  It has been a long time since I've worked with modems, but the audio  
interface should work the same as a sound card under windows.  It should  
appear as an audio device.  Obviously there has to be some difference so you  
can take the phone off hook.  I remember when the win modems came out they  
weren't much more than a sound chip and the telephone DAA.

Maybe someone here knows if a built in modem has an interface compatible  
with a sound card?

--  

Rick C

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We've slightly trimmed the long signature. Click to see the full one.

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