It's not a pin out issue, it is a protocol issue. USB (universal Serial bus) is a different protocol all together than the 8 pin modular (ethernet) you have on the back of the device.
I suspect you will need an ISDN device with an ethernet (8 pin modular) output and a patch cable between the two. It might be easier to find an all in one device like the Cisco 804 series that provides you with an ISDN NT1 terminate, the ISDN 'modem', and a firewall/router.
Good Luck!
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com