That's not a meaningful question. In the USA, when you dial an 800 number, the phone switch does a database lookup to find out which carrier handles it, connects the call to that carrier who can do anything with it they want, perhaps forward it to a POTS number somewhere, or to dedicated trunks, or something more complicated with voice menus, perhaps based on where the caller is, the time of day, load levelling, or anything else they offer their customers. The same thing happens in other parts of the NANP, probably a little simpler in countries that don't have long distance competition.
When you call +1 800 XXX XXXX from outside the NANP, if they handle the call, they route it to a NANP country, probably the U.S., and the call is then handled from there.
R's,
John
PS:
We offered, Europe turned us down. Their loss.