For buyers with a Telekom Surf & Call fare but problems arise quite a different kind. This, however, only if genuine fixed net used, and the router can not be used as a terminal.
The old fax cable (N - "Non-telephone" as opposed to an F-cable for "telephone") my Elsa Microlink did not want to work.
Since I already had set up successfully in a Windows 7 computer that Longshine, I knew now to help me.
Take an extra telephone socket NFN. Screwing and connect to positions 1 and 2 a bell wire. When the splitter small flap slim down in the middle. There is a segment titled TAE. There at the terminal "a" of the bell wire (1) and "b" of the wire (2) Reconnect. Plug the phone cord (F) into the modem and the TAE plug into the middle slot of the telephone socket. Done. This I found out only after several telephone conversations with the telecom technology.
This time I had the items within two days, Super!
Addendum:
For me, the fax also works on USB 3.0
So have fun making and fax.