OCS 2007 R2 SIP address not searchable...Single user

Have a user that is not searchable in OCS by his SIP address ( 1st name, last name ). He is discoverable by the full email address. Strange thing is in our Web Client, he
is searchable by the SIP address. He is the only user that has been reported with this issue with over 1k users in our environment. The affected user is able to resolve any name by the SIP address.