USB modem - Twister MDM7602?

I've been doing some digging (Google etc) to see if I can get a friend's modem working in SuSE9.0. It's the last thing he needs before he can move 100% over to Linux. Anyway, it's a Twister USB 56k, model MDM7602 - sadly yes, it's a dreaded WinModem (what isn't these days?). It's present on the USB bus.... I can see it with any usb inspection tool etc. If I use YaST, it's in the list as an autodetected modem, attached to /dev/ttyACM0. If I config and then attempt to dial out with the modem it coughs out 'cannot connect to device' errors. So, has anyone had any luck with this modem and Linux? C.