Problems trying to install an Aztech UM9800 usb modem (smartlink-softmodem, ST7554) on suse 10.0.

I downloaded the 2.9.10-17 rpm file and installed, got the daemon running at startup. (Confirmed by dmesg output below):
slamr: module not supported by Novell, setting U taint flag.
slamr: module license 'Smart Link Ltd.' taints kernel.
slamr: SmartLink AMRMO modem.
slusb: module not supported by Novell, setting U taint flag.
ST7554 USB Modem.
<6>slusb: slusb0 is found.
usbcore: registered new driver ST7554 USB Modem


When I try to dial (KDE provided dialer applet using wvdial) the modem goes offhook, and I can see in the log where it responds OK to the initialization and (presumably) to the ATDT prompt (my sound card is not working, so I can't actually hear it try to dial). The log shows it never sees a carrier detect, simply tries to dial again (the phone line is fine, the same modem works under windoze). dmesg output shows multiple buffer underruns, followed by some interesting stuff which is beyond me:

PPP generic driver version 2.4.2
st7554: fifo underrun!
st7554: fifo underrun!
st7554: fifo underrun!
st7554: fifo underrun!
st7554: fifo underrun!
st7554: fifo underrun!
... (many, mny more)
sb_unlink_urb() is deprecated for synchronous unlinks. Use usb_kill_urb() instead.
Badness in usb_unlink_urb at drivers/usb/core/urb.c:461
[<d17e899e>] usb_unlink_urb+0x4e/0x80 [usbcore]
[<d12abc56>] st7554_stop+0x116/0x160 [slusb]
[<d12ac480>] st7554_ioctl+0x0/0x110 [slusb]
[<c0169a6e>] do_ioctl+0x4e/0x60
[<c0169b7f>] vfs_ioctl+0x4f/0x1c0
[<c0169d27>] sys_ioctl+0x37/0x70
[<c0102d1b>] sysenter_past_esp+0x54/0x79

Any ideas?

have you looked in the mailist archive of linmodem
linmodems.technion.ac.il/

there is an option dumb mode for wvdial (shot in the dark)