modem not responding to mgetty

Charles Ulrich charles at
Wed Jan 5 08:56:42 PST 2005

Timothy Luoma said:

> This remains all that dmesg shows:
> # dmesg |grep "^sio"
> sio0: <16550A-compatible COM port> port 0x3f8-0x3ff irq 4 flags 0x10 on
> acpi0
> sio0: type 16550A
> sio1: configured irq 3 not in bitmap of probed irqs 0
> sio1: port may not be enabled
> I'm starting to think that my modem (US Robotics that I salvaged from
> an old HP I had) isn't detected by FreeBSD on boot.

This is true. FreeBSD will recognize a hardware modem as if it were just a
serial port and from the looks of it, it's only detecting a single serial
port: the external one. (The 9-pin port that you couldn't identify.) You could
try disabling the external serial port in the BIOS, but I doubt that would
really make a difference.

It's possible that you have a software modem (sometimes called a winmodems)
which requires special windows-only drivers. One way to find out for sure:
google for the model number of the modem plus the word "linux" or "freebsd".
You should be able to discover whether it is a hardware or software modem.

>  If so, would I be
> better off getting a new modem that might be recognized?  It's a 56k
> fax modem, IIRC what WinXP was telling me.  (I tried to save $20 by not
> buying a modem installed by Dell, and I knew I was going to regret
> it...)

No, you would have still regretted it. Most PC manufacturers started shipping
software modems with their machines in the early 90's and these days the only
way to get a hardware modem is to buy one yourself.

If you go out to buy an internal modem, make extra certain that it's a
hardware modem. I know U.S. Robotics sells them, but you'll probably have to
scrutinize the box pretty carefully in order to tell. You may even have to jot
down the model numbers and research them at home before making the purchase.

Even better, buy an external modem that connects to your serial port. (That's
9-pin serial, not USB.) These are always hardware modems, are a lot easier to
debug than the PCI variety, and work with pretty much every operating system
that your computer is capable of running.

Charles Ulrich
Ideal Solution, LLC -

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