When the 800 number owner applied the number from a carrier, he/she had to set if the line accepts calls from US (or Canada), and if the line accpets calls from international. If yes, it means the owner agrees to pay the incoming call cost from those sources. If no, a call from a perticula source will be rejected, even if you dial 001-1877...
That's the way the billing system is working. So I doubt anybody can call 800 from China by PSTN except that number has declared to accept international calls.