On-premises Lync users can't leave voice mail for mailboxes in Office 365 Dedicated/ITAR (vNext)
On-premises Microsoft Lync users can't leave voice mail messages for users who have mailboxes in Office 365 Dedicated/ITAR (vNext). If you examine the connections from the on-premises Lync servers, SIP connections to exap.um.outlook.com show a 504 response.
This issue occurs because a federation SRV record isn't set up in the on-premises Lync domain.
To resolve this issue, follow the steps at Create a DNS SRV record for integration with hosted Exchange UM.
Article ID: 3163886 - Last Review: 11/17/2016 11:22:00 - Revision: 2.0
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