[Would it be correct for me to believe] that the
Fair Debt Collection Practices Act applies to
companies that that regularly try [through means
of interstate commerce] to collect debts . . .
. . . Yes . . .
. . . . not to the original person or company to
whom the debt is allegedly owed [?]
Ordinarily, but not always, because (among other qualifications not
apparently relevant to what you seem to be trying to ask about)
numerous businesses attempt to collect their own debts but, to try to
suggest that some third person is doing that, use a name other than
their own for this purpose, and a business which does that is deemed
to be a "debt collector" for federal FDCPA purposes. However, as you
assume, the term "debt collector" in relation to an individual
consumer does not include the creditor or an officer or employee of
the creditor while, in the name of the creditor, collecting debts for
the creditor.
Many companies contract out their billing to billing
companies (that may be a thousand miles away) . . . .
. . . or maybe not so far away or, as noted, maybe not really
contracted out (separate) companies for FDCPA purposes (a
qualification noted here only because you don't make clear why you
believe it relevant to you to interject the geographical factor you
do).
Are billing companies [in relation to natural persons
allegedly obligated to pay a debt] considered debt collectors
in terms of the Fair Debt Collection Practices Act . . .
. . . Yes (re. which see Sect. 803 of that law, which is codified in
15 U.S.C. § 1692a) . . .
. . . (e.g., do they have to stop calling you if you if you
tell them?)
Yes, depending *how* -- namely, that, to be effective for this
purpose, you must "tell them" in/by a writing (re. which a
short/simple letter suffices). As the FTC summarizes:
If you decide . . . that you dont want the collector
to contact you again, tell the collector in writing
to stop contacting you. Heres how to do that:
Make a copy of your letter. Send the original by
certified mail, and pay for a return receipt so youll
be able to document what the collector received.
Once the collector receives your letter, they may not
contact you again, with two exceptions: a collector
can contact you to tell you there will be no further
contact or to let you know that they or the creditor
intend to take a specific action, like filing a lawsuit.
Sending such a letter to a debt collector you owe
money to does not get rid of the debt, but it should
stop the contact. The creditor or the debt collector
still can sue you to collect the debt
http://www.ftc.gov/bcp/edu/pubs/consumer/credit/cre18.shtm
referring to Sec. 804(c) of the FDCPA (codified as 15 U.S.C. §
1692c(c))
A debt collector who violates this prohibition is suable by the
consumer even if the consumer owes the debt in question.