In article <20011115214508.G15090@nelgin.nu>,
Nigel Reed <nigel@nelgin.nu> wrote:
>The answer is...none, because the kernel doesn't recognise that
>particular modem
>
>isapnp0: <U.S. Robotics 56K Voice INT, USR3090, , > port 0x2f8/8 irq 3 not
>configured
>
>The not configured bit gives it away.
>
>I seem to recall that I fixed the problem with one of my USR modems
>by adding an entry into /usr/src/sys/dev/isapnp/isapnpdevs
>
>Search the netbsd-help or current-users lists because I think this
>has been previously documented.
>
>Regards
>Nigel

Nigel is absolutely right here.
add

    devlogic        com     USR3090         0       USR 56K Voice INT

to /usr/src/sys/dev/isapnpdevs

    make -f Makefile.isapnpdevs

and rebuild your kernel. You should also check that

    com*	at isapnp*

is not commented out in your kernel.

christos