Windows 2003 licensing

I have a Windows 2003 server running a third party application that uses

Oracle database. This application requires authentication to use -

authenticates within app itself not through AD accounts. Currently only

people within the company access the application. However, shortly we will

open it up via web site to our business partners and clients. They will also

require authentication through the application. My question is will I need

to purchase addtional Windows CALs in order for our partners and clients to

use this application?

Thanks