Sometimes you need to modify the Active Directory schema to add new user attributes and then map these attributes to SharePoint user profiles.
The first step in this process is to make modifications to the Active Directory schema. This process is described in the following TechNet article:
Now you need to create a SharePoint user profile attribute and map it to the new Active Directory attribute. Before you can do that, you need to update the schema in the Forefront Identity Manager 2010 on the SharePoint server running the User Profile Service Application.
a) Navigate to the C:\Program Files\Microsoft Office Servers\14.0\Synchronization Service\UIShell folder
b) Double-click on the miisclient.exe application. This will open Forefront Identity Manager 2010.
c) Click the Management Agents button on the toolbar
d) Select your Active Directory management agent (it should say Active Directory Domain Services in the Type column)
e) In the Actions menu select Refresh Schema
f) Click OK in the confirmation dialog box
g) If prompted, specify credentials for the domain account used by the agent
h) A window will open showing the schema refresh progress
i) Once schema refresh is complete, click Close button to close the refresh window
j) Close Forefront Identity Manager 2010
Once the Forefront Identity Manager schema has been updated, you can create a new SharePoint user profile property and map it to the Active Directory attribute.
a) In Central Administration under Application Management select Manage service applications
b) Click on the User Profile Service Application
c) Under People click Manage User Properties
d) Click New property
e) Specify Name, Display Name, Type and other settings for the property
f) Scroll down to the Add New Mapping section
g) Select your Active Directory synchronization connection in the Source Data Connection field
h) Select your new Active Directory attribute in the Attribute field
i) Select Import in the Direction field
j) Click Add to add the new mapping
k) Click OK to save the new profile property
Next time you run the profile synchronization job, the new profile property will be populated with values from Active Directory.