Do these domains draw any traffic even if you don't own the corresponding 800 phone number?
A competitor employs this method; I wouldn't think it would deter most from clicking on your SERP link. They might even pick up the phone before clicking. But it might appear spammy to some.
I throw my 800# in the meta description, but personnally I wouldn't put it in the domain name or the title tag.
Employing a domain like that & not owning the number is lunacy. :)