Using Fax Modems in Sierra

On p. 15 of Take Control of Upgrading to Sierra, I said that some third-party fax modems that come with their own drivers (including a couple of USRobotics models) “should” be compatible with Sierra. Unfortunately, it turns out that they aren’t. If you need to use a fax modem in Sierra, there are a few alternatives open to you (such as running a virtual machine, using an Internet fax service, and copying the old drivers from El Capitan). Adam Engst lays out the options in Lost in Sierra: Five Missing Features.