First, you need to be sure that the right driver is loaded.
Go to YAST>hardware>hardware-information. There you can find a listing of every detected device with properties and with information about the loaded driver (I am using opensuse 10.1).
I don't know it for sure, but I think that the drivers for softmodems are not included in the standard opensuse 10.1. I suppose you need SLED 10.0 or maybe Suse 10.1 .
Here you can find drivers:
For the configuration of the network via modem, I am missing experience.
Hope this helps,