Xircom CreditCard Modem Adapter 33.6 Upgradable and 56 firmware
"Models covered CM33U, CM56
Does NOT Support CM28, CM33, CM56G, CM56T, CEM56, CEM28, CEM2, CEM
This self-extracting archive file contains a flash upgrade for the product.
You should also obtain XM56_1.EXE which contains installation, utilities and drivers released with the product."