As we mentioned before, for Enterprise Voice, Lync requires a dial plan that contains normalization rules that elaborate the phone number typed in by the user and standardizes it to the E.164 format. Normalization rules use .NET regular expressions (http://msdn.microsoft.com/en-us/library/hs600312.aspx).
As a starting point, I have used the
UK-London-Lync.ps1 script generated with Ken Lasko's Lync Dialing Rule Optimizer.
New-CsDialPlan -identity Site:Site001