Exchange Online Autottendant and Lync OnPrem

To integrate Exchange Online AA with Lync, we need to create a contact

https://technet.microsoft.com/en-us/library/gg412978.aspx

Then get Identity, you can run run Get-CsExUmContact

but then if you try to call AA but sip, or number you will get an error (in Snooper).

SIP/2.0 500 Server Internal Error
ms-user-logon-data: RemoteUser
...
CSeq: 1 INVITE
ms-diagnostics: 15014;reason="Hosted Voicemail Policy assigned to the user is not fully configured. Destination or Organization might be null";source="xxxx";appName="ExumRouting"
Server: ExumRouting/5.0.0.0

You will want to run another command to assign policy to this contact.

Grant-cshostedvoicemailpolicy –identity “paste-your-Identity as you see in get command above” –policyname O365

O365 is your policy as you defined in Exchange Online - refer to https://ahandyblog.wordpress.com/cloud-technologies/office-365-unified-messaging-with-lync-2013-on-premise/