HR refused to cover phone calls home that were longer than 3 minutes.  When I pointed out that my other charges were very modest and well under limit -- I don't think it made an impression.  But when they got to the part in my response that said cover the expense or my road trips are over, reason seemed to take hold.  Cell phones, of course, have eliminated this as an issue.
It bothers me that  we would  ever have to  resort to threats to get our employers to live up to their responsibilities.  Fortunately, I have had to resort to threats only twice in forty years (once early in my career and once just two years ago).
I suspect contract workers have some horror stories behind their compensations and re-imbursements.