I just wanted to update this thread based on experiences in Singapore and Hong Kong. The AT&T local number suggestion worked...most of the time. On about 2 occasions (out of many calls trying to get 4 people on the same CX flight via awards), I had an AT&T person get on after I dialed the US number and ask for my AT&T calling card number, or CC. One time I got an automated prompt to do the same. Not sure what caused that as other times it went through fine.

As I had a SIM in Singapore with free IDD calls to the US (and 8 or 16 cents/minute local time charge), it was not a big deal. In Hong Kong, the charge was either 1 HK$ (about 12 cents) or 0.33HK$ (about 4 cents) a minute so, again, no big deal if it failed.

I was also able to call the regular EXP 800 number. I'd get a message saying that it wasn't going to be toll free, and would be charged at the IDD rate, but I could get through.

Cheers.