Issue: Unable to make Lync (Peer-to-Peer) call.

Error: There is more than one contact with your phone number. If you cannot resolve this problem; contact your support team with this information.
Problem Statement:
Whenever user tries to make Lync call or Communicator call user received the above error. This is because more than one user has same LineURI.
Resolution:

1.     Open Lync Server Management Shell,

2.     Type below command:

Get-CsUser | where {$_.LineURI -eq "tel:+11122233345;ext=1234"}

3.     You will get all users who are having above LineURI.

4.     You need to correct LineURL for affected user to unique LineURI.

Cmdlet:

Set-CsUser -Identity "Ilag, Balu" -LineURI tel:+12345678900

5.     Wait to sync LineURI.

6.     After phone number updates try to make Lync call with your buddy.

7.     You will be able to make call without any issue.

Thank you.