Gotcha – Integrating Lync On-Prem with Exchange Online UM

As part of our (Provoke’s) recent migration of our corporate email to Office 365 and Exchange Online, we wanted to include migration of the Exchange Unified Messaging role to Exchange Online as well. Simple enough, and the UCGuys have a superb post that breaks down the process in real simple terms.

However..

We struck an issue after completing the process whereby calling voicemail, or trying to dial the UM dial-in numbers failed. Checking the logs revealed an error along the following lines:

ms-diagnostics: 1036; reason=”Previous hop shared address space peer did not report diagnostic information”; source=”<fe-server>”; dialplan=”Hosted__exap.um.outlook.com__<multipleSMTPdomains>”; umserver=”exap.um.outlook.com”;responsecode=”503″; msexchDomain=”<primarySMTPdomain>”; msexchPeerServer=”exap.um.outlook.com”; msexchsource=”<edgeaccessfqdn>”; appName=”ExumRouting”

Followed by:

ms-diagnostics: 15030; reason=”Failed to route to Exchange Server”; source=”<fe-server>“;dialplan=”Hosted__exap.um.outlook.com__<multipleSMTPdomains>“; appName=”ExumRouting”

Turns out we (and by that I mean me) had made an error when running the command:

New-CsHostedVoicemailPolicy -Identity Office365UM -Destination exap.um.outlook.com -Description “Hosted voice mail policy for O365 users.” -Organization “domain.com”

In my desire to validate blog posts before blindly following them (crazy right!), I’d checked the UCGuys’ NewCsHostedVoicemailPolicy  syntax against the Technet cmdlet library for New-CsHostedVoicemailPolicy, which states for the Organisation field..

This parameter contains a comma-separated list of the Exchange tenants that contain Lync Server 2010 users. Each tenant must be specified as an FQDN of the tenant on the hosted Exchange Service.

Which I duly interpreted as meaning all SMTP domains associated with the Exchange Online tenant – of which we had three. Especially as the example syntax at the bottom of the article does exactly that.

Turns out, that aint gonna fly.

For Exchange Online UM, you must specify one domain only in the Organisation field. And that domain must be one that Exchange Online is authorative for. If you’ve done a cutover migration, that will mean you can probably use your primary SMTP domain, as by dint of the cutover, Exchange Online will be authorative for that domain. However if you’ve done a hybrid migration, chances are good that your on-premise Exchange platform is still authorative for your primary SMTP domain. So best option here is to use your <customer>.onmicrosoft.com domain, as Exchange Online will always be authorative for that one.

This is briefly outlined at the end of the Connect Lync Server 2010 to Exchange Online UM Checklist from Microsoft.