5.1.17 US Robotics (now 3com) Courier/Sportster Fax/Data modems

There are a number of major lines of 3com/US Robotics modems:

• USR Courier V.34/V.everything – those are quite expensive, but really, really good modems. I think those are the best V.34/X.2/V.90 modems around, and they are also very good for class 2.0 faxing. But make sure that you use a recent firmware, as older versions had very bad (and stooopid) bugs in the fax department. You can find out the firmware version with the ATI7 modem command. The ‘Supervisor rev’ version listed should be at least ‘6.5.3’, better ‘7.1.8’ (this is the ‘X.2 upgrade’).

  Fax polling still doesn’t work, and if you send faxes to a modem that can only accept fax with 7200 bps, it will fail with +FHS:25 unless you specify sendfax -M 7200.

  The Courier series does not have voice features.

• USR I-Modem – this is an ISDN Terminal Adaptor with built in V.34/fax mode (“ISDN Modem”). Nice product. Works. The same stuff said for the Courier V.34/V.everything is true for the I-Modem.
• older USR Courier modems – older series without flash ROM, and possibly not upgradable to V.34/X.2 at all, might give problems. Fax was added fairly late, and the first fax-capable releases are very buggy. If you have such a modem, and ATI7 does not list ‘V34’ in the ‘Options’ line, you might try setting modem-quirks 0x20 in mgetty.config. Maybe it helps. But don’t expect too much.
• USR Sportster series – the “Sportster” is actually a range of many different low-end modems. Most of them can do voice stuff, some of them have flash ROM to be upgraded to newer firmware. For data, this modem is quite good. For fax, it might work, and it might not – I have received a very high number of “it doesn’t work at all” reports, and also a number of “it works very well for me” reports. If you plan to buy one, make sure you can return it if it doesn’t work. (See below for some specific issues and workarounds).
• Internal PC card – I haven’t been able to find out yet whether that is a “Sportster” or a “Courier”, but it seems to be a Sportster, with all its negative habits.

Some older USR firmware versions had severe bugs when doing RTS/CTS (that is, hardware) flow control. Occasionally, a byte got lost, and sometimes this confuses the modem enough to abort transmission with the error message

Transmission error: +FHNG:44 (Unrecognized Transparent data command)

Sam Leffler recommends using Xon/Xoff flow control for both fax sending and fax receiving (#define FAX_SEND_FLOW FLOW_SOFT and #define FAX_REC_FLOW FLOW_SOFT in policy.h).

Some day in the future, I’ll make those "quirks" configurable from the config file, but until then, you’ll have to live with recompiling. Sorry. (Upgrade your firmware!).

Fax polling with the USRs is not working, even though the modem claims so. It will work half-way through, but fail miserably later.

When sending faxes with an USR faxmodem, set ignore-carrier yes in sendfax.config. Otherwise it will fail after the first page with a read error and error code -5. (But that is default anyway, if you use mgetty 1.1.16 and up).

For some fax receivers, a problem remains: the USR modems do not want to negotiate 7200 bps transmission speed. If the receiving modem won’t accept 9600 bps, transmission will fail after sending three DCS frames, with the error code +FHS:25. In that case, try setting fax-max-speed 7200 in sendfax.config.

RSPEC errors: some series of USR Sportsters and early Couriers have bugs in the handling of the AT+FCC command. It’s meant to specify the maximum transmission speed, like “14400”, but these modems interpret it as minimum speed, so they fail if sending to a machine that can only do 9600 bps. If you see RSPEC errors in the sendfax log (+FHS:24), try the setting modem-quirks 0x20 in sendfax.config. This will tell sendfax not to set the corresponding AT+FCC parameter.

The USR modems support Caller ID delivery (both the I-Modem series and the analog ones). Switch it on with AT#CID=1 and mgetty should automatically be able to recognize the incoming caller ID. If not, show me a detailed log file...

Firmware upgrades and documentation are available on ftp.usr.de in the directory /pub/USRobotics/modem/....