Lync client showing duplicate numbers on contact card.

A customer contacted me with a request to look into a problem regarding duplicate numbers in the Lync client contact card. When a Lync user would call a colleague, the numbers displayed in the list would be duplicates with normal eight digits and the same number with a + sign in front. After some digging in AD, Exchange and Lync without figuring out where this number came from, I kind of stumbled across the solution.

I created a normalization rule that normalized all numbers starting with a +, removing the + and adding +47(for Norway):

RegEx Matching pattern ^\+(\d{8})$ (for Norwegian eight digit phone numbers, replace with your own digit length), Translating rule +47$1 (Norwegian national prefix, replace with your own).

This change in normalization for workaround purposes turned out to be a valid solution to remediate the problem with duplicate numbers. Seems like Lync is collapsing the numbers based on the newly created normalization rule, thereby de-cluttering the number lookup in the contact card and call rooster.

Maybe this is documented somewhere in MS documentation, but if not, here’s how to fix the problem if you stumble across it 🙂

Comments greatly appreciated.