I found myself with occasion to tell the same story multiple times in the past couple of days, so it seems appropriate to publish it somewhere for easy reliable reference:
Years ago at a programming language conference, I finally met in person someone I'd interacted with regularly on IRC and Twitter. In those contexts, he used a handle of his choosing, and naturally, everyone referred to him by it.
I noticed that everyone was addressing him by his initials. I played along, but eventually asked him directly — in a minute when others were occupied elsewhere — if the use of his initials was his choice.
You see, my friend was from Elsewhere: the conference was in the U.S., while he and his name are not "American", nor Western. Many people seem to balk at saying names that they are not already familiar with, either because of pronunciation anxiety, or much less benign reasons. Dale Carnegie is often quoted on this topic, so I might as well follow suit:
Using a person’s name is crucial, especially when meeting those we don’t see very often. Respect and acceptance stem from simple acts such as remembering a person’s name and using it whenever appropriate.
So, I asked, and my initialed friend indicated that he'd prefer it if I used his given name when speaking with him, but that it was apparently tough for some to pronounce. I asked him to say his name a couple of times, I got it right on my second try, and I used his name as he preferred it in every interaction we had thereafter. It wasn't hard, and he seemed glad that someone was willing to take 60 seconds to show him that respect.
This is simple stuff that is easy to get right and costs nothing.
Some obvious corollaries to the above story:
Someone's "real name" is whatever they say it is.