I would never give out my phone number online to random people, if that's what you meant by calling.

As far as voice chat goes, I feel like it's only awkward the first couple of times you start using it. I used to be extremely self-concious about my English pronounciation and accent, but after using VOIP for sometime, you realize that nobody cares, as long as you're understood. And nobody really cares about introductions and such either, some people like to chat more, some people don't, just like with text chat. VOIP is mostly just an extra tool used for on-the-fly communication in battles. Of course, some people like to use it for socializing in general, but if you just want to raid, you mostly need to be able to listen raid calls and maybe call one or two words every now and then, if it's relevant to the fight.