Plus one on this -- it would be nearly impossible to make a P2P chat system work on our corporate network since we have layers of isolation between users (not t

Plus one on this -- it would be nearly impossible to make a P2P chat system work on our corporate network since we have layers of isolation between users (not to mention about a dozen small branch offices, each with their own independent office, so even if I can Slack the coworker next to me with P2P, I couldn't reach the coworker in Germany that I really need Slack for). So we either need a central chat server on our network, or we use a cloud service like Slack. We used to run Microsoft Communicator (OCS) and availability of that service was far worse than what we've seen with Slack.