flexfax: terminated abnormally: RSPREC invalid response received

[Jakob Curdes <jc@info-systems.com>]

I use hylafax 4.0 pl1 successfully on a linux box with a US Robotics sportster
flash. Recently, with two different senders I had problems receiving faxes. The
connection was ended soon and the log file shows the message 

terminated abnormally: RSPREC invalid response received   

One of the senders succeeded in sending me a fax f
rom his modem while the fax machine repeatedly failed with the above error.


There is an old answer form Sam Leffler in the mailing list  archive that  says 

>This error is easily possible under noisy line conditions or similar
>communication problems.  If the problem is reproducible then contact
>Multi-Tech.  You might also get the sender to lower the signalling
>rate or constrain it on your end using Class2DCCCmd or Class2DCCQueryCmd
>(though you won't want to do this for all calls, just for a test)

Hmm. I found the commands in config(5), but that does not help me 
much. 

>Class2DCCCmd string AT+FCC Class 2.0: command to set modem capabilities        
>Class2DCCQueryCmd string AT+FCC=? Class 2.0: command to query modem
capabilities


Where can I find docuumentation on the 2.0 standards ? 
Or does someone have the right parameters at hand?  

Any help appreciated,
Jacob Curdes