flexfax: Missing TSI, common problem?

["nick s." <nick@troll.soc.qc.edu>]

About 80% of our received faxes are missing the TSI.  While it's
understandable many people do not enter this info in there fax machines, I
do notice that the header of the faxes sometimes will contain information
which would appear to be the TSI (company name or phone number, along with
date/time page number, etc). 

Is this just their equipment not following the fax protocol
specifications, or can a configuration adjustment be made on my side? 

I'm using the hylafax-sparc-sunos5.5-v4.0pl1-pkg binary.

thanks!