Get-ummailbox
Property AccessTelephoneNumbers can't be set on this object because it requires the object to have version 0.10
(14.0.100.0) or later. The object's current version is 0.1 (8.0.535.0).
    + CategoryInfo          : NotSpecified: (:) [Get-UMMailbox], InvalidObjectOperationException
    + FullyQualifiedErrorId : [Server=EXCH01,RequestId=1b92d7d4-d4dd-41ea-8eb6-3e4e15e1cde5,TimeStamp=6/15/2015 3:5
   1:31 PM] [FailureCategory=Cmdlet-InvalidObjectOperationException] FE250A79,Microsoft.Exchange.Management.Recipient
  Tasks.GetUMMailbox
    + PSComputerName        : exch01.net

not sure why im getting the above error.

Hi

Are you running 2 versions of exchange in your organization? If so have you tried running the command on the newer version?

yes ex2007 and ex2013.

tried directly on the ex2013 running 2012R2. same error.

Hi totalnet,

Thank you for your question.

You could move this UM mailbox to Exchange 2013 then run the command to check if the issue persist. Because the mailbox require Exchange 2010  or later version.

In addition, if you want to run Get-UMmailbox, you should be granted to Exchange recipient administrator role permission.

If there are any questions regarding this issue, please be free to let me know.

Best Regard,

Jim