VOGONS

Need help emulating an phone line

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First post, by kotel

Posted on 
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Hi,

So recently I got an very good idea to make an emulated phone line at home 😄

I got two laptops with soft modems (one agere, second conexant). Installed putty on them, set correct COM port and baud rate (both COM3 and 57600 baud) and did the following commands:
Reciving laptop

at
OK
ats0=1
OK
ata

And then it started to await for calls
Caller laptop

at
OK
atx3 (or atx0)
OK
atdt1234

But they didn't do the handshake at all. Reciving was searching for any calls but the dialling laptop only made the number dial and "buuuut buuuut buuuut...." and so on
Tried an mix of commands of atx3/4/1/0 on both laptops but still nothing.

Tried to put 9vdc, 12vdc and 24vdc on tip and ring (and vice versa) but no go. Only got an popup saying that

this phone line is not supported by your TOSHIBA modem

on my toshiba laptop (the one with agere modem).

Anything I'm missing here? I don't have any fancy PBX or dialup centers at my disposal.

"Sent on a mission, to protect the last treasures. Through struggle and strife we can see the light. Even if our mission is partially complete, Our efforts are not in vain.
Let that be our legacy."
-Stronghold 5-5

Reply 1 of 1, by kotel

Posted on 
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Okay the issue was the power source on the tip and ring. Using an normal 9V cell everything works and I get kinda good handshake but it's still kinda corrupted. At least it now connects at 28k, so that's something.

Now why would it hate my benchtop PSU set to 9V 0.5A? Maybe the PSU has little to no ripple and the modems expect mid/high ripple on tip and ring pins?

"Sent on a mission, to protect the last treasures. Through struggle and strife we can see the light. Even if our mission is partially complete, Our efforts are not in vain.
Let that be our legacy."
-Stronghold 5-5

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