In the event an employee cannot get his/her email working on their new phone, take a look in the EMC to see how many mobile devices are associated with their account. If it is 10, Exchange will not allow another to be added.

The enduser may get a message like this alerting them of the issue:
From: Microsoft Outlook
Subject: Error with your new mobile phone partnership

You have 10 phone partnerships out of the maximum allowed 10 partnerships. After you reach the maximum, you can’t create additional partnerships until you delete existing ones from your account. To do so, sign in to Outlook Web App, click Options > Phone > Mobile Phones, and delete any unused partnerships.

To check or remove from the Exchange Management Console (EMC), find the user, then click “Manage Mobile Phone”

 

 

 

 

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Look at the ‘Last Synchronization Time’ to identify those devices that have not been used for some time

The GOTCHA here is that if the old device(s) cannot be reached by Exchange (which is often the case since the user has probably had multiple new mobile devices since) you cannot remove via EMC, but must do so via PowerShell:

Get the Device GUID

                Get-ActiveSyncDevice -Mailbox <username>

Right-click to use the ‘Mark’ feature and copy the GUID, to paste in the next command

Remove the device

      Remove-ActiveSyncDevice -ID <DeviceGuid>

NOTE: If you look back in the EMC WIHTOUT refreshing, the devices will probably still be there. Once you refresh in the Actions menu they will be gone (or use the first powershell command)