Like Michael Mitzenmacher, I also use skype to collaborate on research projects. But not for voice calls. For me, chatting is much more convenient. I am not sure why, but I can think of some possible reasons.
One advantage of chat is that it protects your privacy better (your correspondents can’t hear you eating). Chat is also less intrusive: Easy to ignore an iconified window in your dock which is getting filled with your friends’ ponderings, but not so easy to ignore them broadcasting their conversation in your office. Then there is the less restricting etiquette — We are programmed to regard gaps in phone conversations as awkward, so it is difficult to take a break now and then. With chat, it’s no problem.
Voice conversations must have an explicit beginning and end, whereas in chat it’s just an infinite stream of messages. You can think about the argument your friend just proposed, and then check your mailbox, and then take a coffee break and then forget all about it, and then it comes back to you, and you send your response in the evening and start a new conversation. If you were having a voice call then either at some point you have to declare `I am hanging of. Will think about it. I will call you tomorrow at 18. Regards to Sabrina’ thereby wasting time and energy handling the social interaction, or you are not hanging off and then your friend is still around you the whole day.
But maybe the reason I prefer skype has nothing to do with the privacy and complexity of the interaction, but it is simply because writing actually helps me concentrate, while talking is a distraction. I know this is true because when I work alone on a problem I often write on a piece of paper or a whiteboard, but I almost never talk to myself loudly
There is one disadvantage to chatting on skype though. You get strange emoticons when you write latex code. But it still beats saying `open parentheses, close parentheses’ all the time