How to assign Lync Dial plan to all the Users in a Domain
The following command is used in PowerShell to grant dial plan to all the users in a domain.
Get-CsUser -OU "OU=<>,OU=<>" | Grant-CsDialPlan -PolicyName<Policy name>
Dial plans is a named set of normalization rules that translate phone numbers for a named location, individual user, or contact object for purposes of phone authorization and call routing.
https://technet.microsoft.com/en-us/library/gg398547.aspx
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