I have a client who wants to set up a fax server in their office. I'd like to use HylaFAX under Ubuntu, but I'm a little shy to spend money on hardware for Linux, particularly a modem given the whole Winmodem issue. So to ask two different questions in the same post:

First, what are the most reliable ways to tell if a modem is supported in modern releases of Linux? It's nice when a manufacturer specifically mentions Linux support. Failing that, do you check the kernel docs? Chipset type? Other keywords on the modem's spec sheet?

Second, what specific modem would you recommend?


The HylaFAX Handbook has some documentation about making sure you have a compatible fax device. According to that document, external serial modems will work almost without exception, but some external USB modems may be softmodems and require a driver. Regarding internal modems, that document references some chipsets and model numbers that are known to work.

Once you find a device that you intend to use, it probably wouldn't hurt to search for it in the hylafax-users mailing list archive to see if another user has encountered a problem with it.

The HylaFAX website also has Hardware Compatibility List.

  • 1
    Thanks for the pointers to back to HylaFAX's own site. Users on the mailing list seem reluctant to recommend a modem and the existing compatibility list is a bit out of date, but at this point I'm leaning towards a TRENDnet TFM-560X external serial modem. – Annika Backstrom Sep 15 '10 at 15:54
  • +1 to all for the mention of external serial modems. This will be the easiest way, trust me. – LawrenceC Feb 18 '11 at 12:22

External modems that plug into a serial (RS232) or USB port usually have all the necessary electronics. Most Winmodems (requiring Windows software to supplement their deficiencies) are internal. “Hayes compatible” or a mention of compatibility with DOS, OS/2, Linux, SCO, or anything other than Windows is an indication that the modem will just work under any OS. If in doubt, look for a model that other people have used under Linux, perhaps second-hand.

  • I can't think of any RS232 serial modem exceptions, but in my experience, most USB modems are Winmodems and require special software on the host computer to work. – Jim MacKenzie Sep 15 '18 at 18:21

As much as this question is very old and answered. I would like to add something further.

For USB modems, "cdc-acm" compliant USB modems will present themselves as a serial device. They are usually self contained and small, with all required hardware. Latest verisions of linux kernel has a module to support these kind of devices out of the box.

Some examples of modems known to support this cdc-acm standard (you'll have to do some diggging) are http://www.usr.com/products/modem/modem-product.asp?sku=USR5637 and any modem containing the Conexant 93010 chipset (I am using the latter myself, and they are quite inexpensive). As Gilles mentioned in his answer, if the manufacturer mentions linux support, then it probably is cdc-acm compliant.


If you need a USB modem, choices are few and far between for hardware modems. These are the modems you need to work with Linux and BSD. Software modems, which offload most of the processing work to the host computer, generally don't work well on Linux and BSD. (There are some old drivers for some forms of softmodem hardware, but they seem to no longer be updated and don't work with modern kernels.)

While there are few USB modems that will be suitable, this is one that I can recommend - the US Robotics USR5637. I own a couple of these. It's a nice v.92 modem with 3 LEDs and real modem hardware inside. The real shortcoming of this modem is the lack of a speaker, so you can't hear what's going on. You could always hook up an RJ11 Y adapter and a phone if you have trouble and want to listen to what's happening, even if this isn't ideal.

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