I’m teaching a small introductory workshop on the use Microsoft Lync (v.2010) within the enterprise, and that sometimes leads to somewhat puzzling situations. One of those comes up when you log into Lync – with the same account – on multiple devices, say your PC and your smartphone. Yes, your status is reflected correctly on both when you change it on one of them; IM conversations are another matter.
The Lync Insider has a good explanation on the subject
(including a link to a few possible workarounds), and one of the commenters summarizes it neatly:
…IM conversations aren’t shown on all of these logins – the first message someone sends to me is sent to all endpoints, and then whichever one I then use to reply is the one that has the conversation window, the others are left with just the first message…
So you can use multiple devices, but you’ll have to rely on Outlook to keep a full log of all your IM chats.