I got interested in acquiring a PABX, maybe the Excelltel MS208. I have no experience in configuring them but guess it can't be impossible to learn.

I found some with google (e.g. https://m.made-in-china.com/product/Excelltel … -775597055.html) but @3dnow could you advice if you know a good place to order from that ships to EU?

Your observation of Courier always requiring dialtone makes no sense. Have you confirmed the dip switches are (were) appropriately configured and the modem initialized with AT&F1 ? I understand this is not relevant for you anymore but nevertheless its interesting.

OS/2 is interesting too! Still to be installed. Last time I tried the install failed mostly due to too large hdd. I have the original retail package with all CDs and printed manuals etc

486man_ wrote on 2025-01-17, 00:36:

OS/2 is interesting too! Still to be installed. Last time I tried the install failed mostly due to too large hdd. I have the original retail package with all CDs and printed manuals etc

For OS/2 Warp 3 (whose only form of networking is Dialup unless you've got Warp 3 Connect), an update is required unless whatever you're dialing into supports SLIP. For more information, see Warp 3 - IBM Internet Connection. I've not tried dialup on Warp 4, but I expect it supports PPP out of the box. Dial-up on OS/2 versions older than Warp 3 probably requires 3rd-party solutions just like on DOS.

3dnow wrote on 2025-01-16, 05:39:

Veeb0rg wrote on 2025-01-15, 20:54:

matti157 wrote on 2025-01-15, 13:50:

I read this tutorial for 56K, for me is too much 😥
https://web.archive.org/web/20240716065145/ht … 6k-dial-up.html

Yeah, unless you come across a deal its pretty expensive to get a 56k connection going. Digital modem stuff has gotten crazy expensive the last few years.

Lucky you getting that digital modem pool to go with your router. For now I'm going to stick with 33.6k. My current project is creating a dial-up file server protected by a USR Courier with dial security.

Following up on that, It arrived today with no modem cards in it. I've contacted the seller to see what can be done about it. There only one listing for the modems on ebay and they would blow the budget plus there's only 2 of em. Back to the drawing board.

Veeb0rg wrote on 2025-01-19, 16:53:

Following up on that, It arrived today with no modem cards in it. I've contacted the seller to see what can be done about it. There only one listing for the modems on ebay and they would blow the budget plus there's only 2 of em. Back to the drawing board.

BALLS! We were so close to affordable high speed dial-up home internet. There's gotta be an easier way to do this. Imagine if V.92 analog modems could communicate with each other using PCM since ITU-T V.92 supports both PCM upstream and downstream. Maybe some special firmware for some V.92 US Robotics modems that causes them to identify as digital modems during the handshake, tricking the client modem into attempting a V.90 or V.92 handshake instead of V.34. Obviously this is not what the standards were made for, but has it ever been attempted before?

486man_ wrote on 2025-01-17, 00:36:

I got interested in acquiring a PABX, maybe the Excelltel MS208. I have no experience in configuring them but guess it can't be […]
Show full quote

I got interested in acquiring a PABX, maybe the Excelltel MS208. I have no experience in configuring them but guess it can't be impossible to learn.

I found some with google (e.g. https://m.made-in-china.com/product/Excelltel … -775597055.html) but @3dnow could you advice if you know a good place to order from that ships to EU?

Your observation of Courier always requiring dialtone makes no sense. Have you confirmed the dip switches are (were) appropriately configured and the modem initialized with AT&F1 ? I understand this is not relevant for you anymore but nevertheless its interesting.

OS/2 is interesting too! Still to be installed. Last time I tried the install failed mostly due to too large hdd. I have the original retail package with all CDs and printed manuals etc

Excelltel most commonly sells their units on Alibaba, but it may be possible to order directly from their website. Maybe try emailing them.

About the Courier:
You're right, it makes no sense! I tried all the &F presets, jumper configurations, X settings, and S-Register settings that apply to dial tones and carriers; and it still does not work. In theory all (smart and not acoustically coupled) modems should support blind dialing but in practice their firmware might indicate otherwise. I have two USR Courier 3453c modems; one is used and the other is new. Neither worked with my DIY powered phone line (would always return "No Dial Tone" regardless of settings) and only worked on a proper line connected to a CO or PBX.
The biggest tell weather or not a modem truly supports blind dialing is whether or not it supports blind answering. I have two USR 5686G fax modems that will always answer and handshake on the DIY line when given the ATA or ATH1 commands even when configured to wait for a dial tone. I also have two USB softmodems (Zoom 3905 USB and a Dell Conexant RD02-D400 USB), and another Dell Conexant D850 internal PCI softmodem that all answer and handshake on the DIY line with ATA even if told to wait for a dial tone in the MS Windows modem settings. But both Couriers and a Dell Intel internal PCI softmodem all hang up after a couple seconds reporting "No Dial Tone" regardless of the settings I use. I actually thought that the Intel modem was broken since it had been sitting in a bin and collecting dust for over a decade (and it does not have a diagnostic mode unlike the Couriers), but it worked perfectly when I put it back in my XP machine and connected it to the MS208 PABX.

TL;DR:
Not every modem supports blind dialing even though they should in theory.

3dnow wrote on 2025-01-22, 16:00:

TL;DR:
Not every modem supports blind dialing even though they should in theory.

I seem to remember some of the modems I had supported leased-line mode. I've never had two at the same time so I didn't test that. Those would need to be able to blind dial and answer but I'm also wondering about the line itself - does it need to be powered? Or can I just use 1km long copper pair connected directly on both ends? Asking because I've just got my hands on busted USR modem but I might be able to fix it. I think one of the RAM chips is dead, it gets very hot for some reason.

Deunan wrote on 2025-01-23, 12:00:

I seem to remember some of the modems I had supported leased-line mode. I've never had two at the same time so I didn't test that. Those would need to be able to blind dial and answer but I'm also wondering about the line itself - does it need to be powered? Or can I just use 1km long copper pair connected directly on both ends? Asking because I've just got my hands on busted USR modem but I might be able to fix it. I think one of the RAM chips is dead, it gets very hot for some reason.

The Courier does support leased line mode but you need a synchronous serial port expansion card and cable for both computers. The serial port built into most older PCs and the serial cable that comes with the modem are asynchronous. Here is what the user guide says about setting up the Courier for leased line operation.

Before you tear apart the board run the diagnostics. More specifically the analogue loopback tests for the transmitter and receiver. Of course I'm assuming that your modem even works at all.

3dnow wrote on 2025-01-23, 13:36:

The Courier does support leased line mode but you need a synchronous serial port expansion card and cable for both computers.

That's not correct. I read the link you posted and it does cover synchronous operation as well as leased line mode but they aren't necessarily linked. You can run async in leased line mode.

maxtherabbit wrote on 2025-01-23, 13:48:

That's not correct. I read the link you posted and it does cover synchronous operation as well as leased line mode but they aren't necessarily linked. You can run async in leased line mode.

You're correct as stated here. They should have been more specific in the manual. The way it is written implies that hardware capable of synchronous operation is required for leased line operation when that is not actually the case.

Regardless, leased lines are not powered so blind dialing should work, but only for leased line operation. You know I actually have two couriers of the same model. Maybe I should try setting up a leased line between them.

Can confirm that leased line operation works between them. I was able to make them handshake over a non-powered phone line and send files using zmodem and minicom.

Seems useful for file transfers between to computers, but I'll leave it to the experts to determine how to setup a dial-up leased line ISP. By the way you're still going to be limited to 33.6K despite the fact that leased lines have no CO nor analog to digital conversion.

I have two external modems. One is a bit unknown "PENTAGRAM" brand, seems to wok but I have no docs for it so I'm not sure it can blind dial or work on leased lines. The US Robotics modem is dead. Sometimes it randomly lights up the LEDs on power-on but that's it. I got it free so can't complain, will try to replace the suspect SRAM chip with hot air at some point.

If both could work on leased line I'm pretty sure I could set up PPP daemon on Linux box to create my own "ISP" except no public IPs - not that I want that. I think even RPi with serial to USB dongle could be such router. I know it's easier to just install ISA Ethernet card into the machine but this looks like a fun experiment. And since these are external modems any computer with RS232 port can work with them.

I repaired the USR modem, turns out both SRAM chips were dead and had to be replaced. However the Sportster series do not support leased line and my Flash sure also doesn't. At the very least it is already V90 so I don't have to update the FW, and I even found a manual. The "Pentagram" is just some OEM with Venus V.90 from Lucent Technologies, also no leased line support but at least the chipset is quite well documented. Both modems support blind dialing with no number with just ATD, but might need ATX1 or ATX3 because the default config expects to hear the dial tone. So, after figuring out how to power both at the same time (because one PSU was missing and the replacement got broken in shipping) this is what I got:

Sportster:
>ATX3
OK
>ATD

Venus:
>ATA
CONNECT 33600 V42bis

Sportster:
CONNECT 33600/ARQ/V34/LAPM/V42BIS

I'd say it's a success. I know I won't get 56k without a special modem, this is already good enough considering I used 2m of RJ11 patchcord, unpowered, to connect both modems. The Sportster actually outputs some sort of pulsed tone when doing blind ATD but sadly it's not picked up by the Venus, even if I put it off-hook with ATH1. I suppose auto-answer will not work without power on the line, that will be the next experiment I guess.

So, TL;DR: For transparent leased-line operation the modems must support it natively but a link can be established manually on unpowered line with some dumber devices as well.

Okay I got the dialup connection going, but sadly I get no internet on the client. I have an working phone line emulator, but that only allows me to authenticate and handshake the modems.

I get tcp/ip error 733 after the modems handshake and if I reset the server 2k3 r2 prior to that. No idea what I'm doing wrong. I don't get the option to add any PPP/modem under NAT/basic firewall settings in RAS configuration snap-in.

Any ideas?

Okay so now it fixed itself? I don't even know what's happening anymore....

So to wrap this up for total newbies so they won't have to go through hell
1. you use the "add new network connection" feature on windows to dial into the server using the login and password you've set
2. you have to have an phone line emulator which has both 9VDC on hook voltage (standby voltage) and atleast 16VAC off hook voltage (AKA "ring" voltage)
3. you can create the landline emulator quite easily at home using an 16VAC coil and an 7805 VRM for relay coil power with an 7808 VRM for on hook voltage (can be also an 7805 with an 5v zener connected to the GND pad)

...or just ask chatgpt for help. This is how I did it.