OnPrem Lync Server 2010 cannot direct calls to O365 UM

Recently I have had the opportunity to work on multiple OnPrem Lync Server 2010 (Lync) deployments integrated with O365 Exchange Unified Messaging Servers (UM).   Issue Unable to route calls from Lync to UM. If you look at traces from the Lync Edge Server (with SipStack component traced) You should see an INVITE outbound to…

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