Kerry.
From a legal standpoint, you have nothing to worry about. If this is an OVERSEAS book, trying to file a collection against you, they will still need to use an AMERICAN debt collector to have any type of legal legitimacy whatsoever.
ALL American debt collectors (whether they do or not is another story) are bound by the Federal Fair Debt Collection Practices Act, as well as your state's fair debt collections act. I live in Texas, we have a very extensive debt collection code that must be followed, otherwise these debt collectors can be sued for damages, or fined.
The bottom line is, NO LEGITIMATE REAL DEBT COLLECTOR, with any RECOURSE IN AN AMERICAN COURT OF LAW FOR A JUDGMENT LIEN ON YOUR PROPERTY DUE TO YOUR PERSONAL DEBT, would EVER legally be able to call you at 3AM, OR ANYONE ELSE besides you to let them know of the details of this debt.
Trust me, this overseas dickhole is SOL. Come file a judgment lien in America for a ********** for your illegal sportsbooking operation. LOL - that's a 100% pure joke and I can guarantee that. Any "debt collection" or "legal threats" are just pure hot air.
.....now whether or not he sends Julio Ballesteros over to break your kneecaps, well....that's a totally different ballgame.
Good luck man.