Phone line is busy - Connecting old modems for fun. Setup PSTN?


First of all, I am a complete beginner, and I have no knowledge about this program or how modems and phones work. I collect old computers and I want them online using old modems of different kinds. Right now I am trying with a regular 56k modem,v90 or something like that using winxp.

The server:
Old pentium 4.
DAHDI Version: 2.11.1 Echo Canceller: OSLEC
Asterix version: 13.17.0
I have a tdm400p with 4 fxs modules. There is no molex power input on the card. All 4 led’s are green on the card.

When I try to dial something on my modem, it just says, “phone line is busy”.

I did not get any dial tone before, then I did stuff, and got “phone is busy”.
But I need to set up PSTN I guess? I tried to google this, but I can’t figure out completely how to set this up with my setup, how to get internet in through lan, and shared out to my modems.

Any help, suggestions are really appreciated ::slight_smile:

You can’t use modems for voice. That was never their intention, they were to do data. If you have a POTS line then you already have the ability to do voice because that’s what a POTS line does (regular phone service). You use the modem to do data like dial-up/DSL.

So a TDM400P with 4 FXS ports means it can support 4 POTS lines that are plugged into it.

So if I understand, TDM400P with FXS can do POTS which is regular phone service for use with phones, but it can’t talk to a modem? There is a guy on youtube, search for " Using modems without phone lines"

But, he is connecting to a BBS though, and perhaps that’s not the same as being able to get internet access?

Modems send/receive data. You cannot and never been able to talk over a modem like a normal call. It’s sending data the entire time. Those weird tones that you hear during a FAX or dial-up when the modem is connecting, that’s the data stream.

You cannot use a modem to do a voice call, it just doesn’t work that way. So what are you actually trying to do?

I want to use old modems and connect to BBS and Internet. I collect old computers, like Commodore 64, Amiga, 486 PC and such. I want to connect them to the internet or BBS not using modern solutions, but use older hardware.

OK the thing is none of that has to do with VoIP or the PSTN. You want to use a modem and connect to the Internet that way, go for it. You’ll then need to setup your network to use the modem as its route to the Internet. So you’ll need some switches and understanding how routing works and what you need to do with the network to set those systems up.

If you want to connect to the Internet and BBS systems with the modem then you’ll need someone that offers Dial-Up service plus, of course, a POTS line. Because when you use a modem it must connect to another destination that has a modem (or something along those lines) as well.

If you want to connect tot he Internet just using old hardware, then that means you need a DSL/Cable/Fiber style connection and that again will still involve setting things up on the network and routing things the way you want. At this point the modem is pointless because it can’t be used to connect to anything remotely.

You will need to make a decision. Because this is from your original post but your last post says you want them on the Internet without the use of modems.

What? :stuck_out_tongue: Perhaps you read wrong on the last post? Where I said I don’t want modern solutions. I didn’t say “modem” but “modern” But thanks for the reply, I need to read up on how all of this works I think.

Oh yeah, I read that totally wrong. However, the rest of what I said applies. Reading up would be a good start to give you an idea of what you have and what each device is actually capable of doing.

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Hey guys, maybe I’m not reading this right but you most certainly CAN use modems with an asterisk/freepbx system. First, they have to be internally mounted, (ie. pci modem), no serial connected modems here. Next, the modem has to have the right chipset so that Zaptel can work with it.

I’ve done this a long time ago and probably still have several modems that qualify for this. I haven’t done this in years and I have no clue if zaptel even works with these old modems anymore.

I do remember that the audio quality wasn’t that good and you had to tweak it quite a bit.

I wouldn’t waste my time with hooking modems to analog POTS lines unless you are trying to relive your youth…


Here’s a little fun :slight_smile:

Build a server and add pci modems and a pppd service, then plug your client machine’s modems into them via

Then the fun bit , configure. It all !

Yeah, the modems are not supposed to be installed on for example the 486 pc, not the pc running asterix. But the point was to relieve my youth not to be practical :slight_smile:

Looks like fun :slight_smile: Although it seams like it’s not for internet sharing.

How so not “sharing”?

plus a $20 goodwill pc with pci-express and network.

you will end up with 8 tty’s inside the server that are directed through the pppd daemon to the big wide world , each interface will have a private IP and each IP can see all the other internal ones, use a /28 or bigger network, and of course have the default route to internet through the ethernet port.

To really relive your youth you can replace the ethernet card with a serial port and an acoustically coupled modem, a 2500 phone and a compuserve account

oh I just briefly saw the guide offering file sharing but nothing about accessing internet, but if that works it would be great :slight_smile: That 8 modem card was a bit overkill for my needs though, but interesting to know that it exists

Then , minimalisticly

USB 56K Voice Fax Data External V.90 V.92 Modem With Dual Ports, Compatible With Windows 98SE/2000/ME/XP/Vista/Win 7 and Support Auto-Dial, Tone and Pulse Dialing, Auto Answer, Auto Retrain (Black Color)

And a Raspberry pi

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