Customers are very concerned with finding out if I'm a foreigner or not.
So far I haven't seen too much explicit racism, though coworkers have reported some. But nearly every caller eventually asks "where are you physically located?". Occasionally a naive soul will be surprised that I'm not in their town. But mostly people are delighted that I'm in North America. Sometimes they then explain how hard it is to talk to people in other countries.
I'm not completely unsympathetic to these people; our company, for whom North-American techies are a big selling point, have recently started outsourcing sales staff to India and the Phillipines. And those sales staff are noticeably worse at processing people's orders correctly. And I'm keenly aware that it's hard enough for people to talk about technology when language isn't a barrier.
However, xenophobia is also a big part of this. People are very reassured by me in part because I sound 'American'. As one lady put it: "I know you'll be good because at least you're not one of those people in another country". (My reply: "I hope that's not all I have going for me.")
I have an unusual, unplaceably-foreign-sounding name. Which means that a lot of calls open with a quick interrogation about where I'm at, how my name is spelled, etc. It's pretty annoying. (There are a handful of techs in our department with names that are actually obviously asian; I imagine they find this waaaaaay more irritating than I do).
One lady told me "I know you all are good because you're Amurricuns." I said, "We've got quite a few Canadians on staff". She said, "Well, Canadians are okay. They're just like us".
Or, sometimes, like this morning, after talking to someone for an hour and a half, someone will blurt out "You're in Thailand, right?"