[USR-TC] Where to get v4.1.1 code for Quad V.34 Dig Modem?

Trying to add additional channels to RAS solution without changing everything else. 1) Is it possible to backrev a Quad V.34 Dig Modem NAC (08U000) from v5.10.9 to v4.1.1? 2) If so, where would I get the code? TIA, Terry G. Phillips