After a resource room mailbox account has been created and enabled as shown previously, the account will synchronize from the Exchange Online forest to Lync Online forest by using the Windows Azure Active Directory forest. The following steps are required to provision the LRS account in the Lync Online pool. These steps are the same for both an existing resource mailbox account or a newly created account (confrm1 or confrm2), because once they are enabled in Exchange Online, both of these accounts will be synchronized to Lync Online in the same way.
PS C:\Windows\system32> Import-Module LyncOnlineConnector
PS C:\Windows\system32> $cssess=New-CsOnlineSession -Credential $cred
PS C:\Windows\system32> Import-PSSession $cssess
PS C:\Windows\system32> Enable-CsMeetingRoom -Identity $rm -RegistrarPool "sippoolbl20a04.infra.lync.com" -SipAddressType EmailAddress
You can obtain the RegistrarPool address where your Lync users are homed from one of your existing accounts by using the following cmdlet to returns this property, (among others:
PS C:\Windows\system32> Get-CsOnlineUser -Identity ‘firstname.lastname@example.org’
PS C:\Windows\system32> Set-CsMeetingRoom confrm1 -LineURI "tel:+14245231111"