Der USR-Support hat geantwortet. Sie haben das Modem unter Sierra getestet. Soll an Apple liegen m/i ...

... "After testing the Modem in Mac OS Sierra, it looks like Apple has removed support for fax modems for faxing. The modem can still be used for dial-up connections, but looks like there is not way for the modem to be used as a fax device anymore. We are currently investigating the issue, however it is something that would need to be fixed by Apple and not by us. Sorry for the inconvenience..."