I have Lync 2013 installed in our environment. I see that once I reassign an older phone number it still shows up in Lync.

I have checked all AD attributed as well as this article with no luck.

https://support.microsoft.com/en-us/kb/2435699?wa=wsignin1.0 

Any pointers are appreciated.

Hi,

Did the issue happen only for several users or for multiple users?

Please set the Lync client policy parameter AddressBookAvailability to WebSearchOnly.

Then update Lync address book on Lync Server side with the following Lync Server Management Shell: Update-CsAddressbook.

Then test the issue again.

Best Regards,
Eason