See, the different Battle.net servers are hosted by several companies. Normally, the servers are communicating properly, meaning that you can see\\play with people on other servers. From time to time some servers lose connection with the others, meaning that you cannot see or play people on other servers. Sometimes you can still see the person on the list of the people in a channel, but you can\'t talk to\\hear them. Eventually the servers restore the connection and Battle.net works as normal. Its just a matter of waiting for the split to blow over.
