I am using Ubuntu 8.10, an on-board Conexant-based winmodem, the Linuxant HSF driver (the free 14.4k one, specifically hsfmodem-7.68.00.14full), and kppp.

This setup initially worked, but for some reason has started failing. I can address the modem and send it commands, and it responds as expected. ("ATZ" returns "OK", etc.) However, and ATDT command no longer dials. I can hear it pick up the phone line (using an extension phone), but no dialing. I have set kppp to dial without waiting for dial tone, even though I have verified dial tone is present.

I removed and reinstalled the Linuxant driver to no avail. I deleted the modem from kppp and re-added it, to no avail. I have not removed and reinstalled kppp yet, but I don't think that is the problem. I also tried using Putty to address the modem, and I see the same results. Modem respnds, but ATDT does not dial.

I dual booted the computer to Windows Vista (yeuch!) and the modem works 100% - dialing perfectly.

Initially this worked and I established several dial-up connections using Ubuntu and all the stuff I mentioned in the first paragraph above. I have no idea why it stopped working, I didn't do anything to Ubuntu that I'm aware of (no new packages added, etc.)

Any ideas? Thanks!

Here is a guess ... possibly the problem is due to the modem initialization string.

If Windows works, then you can view the init string by enabling a modem log and then dialing out within Windows. The modem log (control panel - phone and modem) can be viewed to see the conversation.

You should be able to take that init string and configure this in the modem properties in KPPP ...

Thanks. I will try looking at that. However I suspect it won't help much. I've tried AT&F (factory defaults) followed by ATZ (reset). Immediately after that I tried the ATDT. I have not run into a modem that wouldn't at least dial after this sequence. Maybe not connect under certain circumstances, but at least dial. I will look at what Windows (yeuch!) has to say about the init string it is using anyway. You never know. Modems are kind of a pain under Linux, but this computer is one I'm configuring for my parents, who don't currently have broadband access. What gets me, however, is that even if this free Linuxant driver works, I will have to pay Linuxant $20 for the "real" driver that goes up to 56k (their free one is limited to only 14.4k - unusable speed). Paying that much for a driver just sounds so un-Linux-like, despite the justifications their website tries to put forth for charging so much.

Does anyone know an easy to obtain, REAL hardware modem, PCI bus, that will fit in a slimline PC half-height case (a Dell Inspirion 530S specifically)? Or a linmodem that has free, quality drivers available?

This could have been the init string. I don't know for sure. What I did was remove the kppp package and used the pre-installed "wvdial" instead. It's companion program "wvdialconfig" will try to create an appropriate init string for your modem. Whatever it did in my case, it did correctly.

I did not go back to try and debug the used-to-work-but-not-anymore kppp. wvdial is a commandline program whereas kppp is GUI. I really wanted commandline in the first place, but did not know about wvdial until after I researched further while trying to debug kppp.