So I was contacted in IM today by a past colleague (Hey Steve) now doing some consulting and he brought up this issue and trying to find the value as well as some background.
The issue came up with a customer who wanted to have what is referred to as persistent chat. We don't position ourselves as being a Chat solution but we do have the ability to keep a conversation window open which satisfies that request. The reason you would not want to make this change just because it looks good in general is that you could negatively impact our MPOP (Multiple Points of Presence) functionality. We support up to 8 endpoints by default, on the Forest properties and User tab - Maximum devices per user - 8. This would mean that if I signed in to Communicator on my desktop and opened an IM window with my entire team and then went downstairs to a training room and signed in again, I would not get any of the IM conversation from the team because it was not not timing out.
If you were to call and speak to me on this subject I would have you consider the impact of changing MPOP to 1 so that if you signed in on another endpoint you would sign yourself out on the other system. Now this is not necessarily the greatest solution overall but does help avoid those helpdesk calls when people claim to not be getting IMs from peers.
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