Depends on the web service.
BTS 2004 comes with a standard SOAP adapter which works with most WS-I Basic Profile web services. There are some limitations particularly with arrays.
If you need and WS-* functionality then you might have to upgrade to BTS2006, There is the WSE3 Adapter from AdapterWorx http://adapterworx.com
The next version BTS2006 R2 (currently in beta) has a built in WCF adapter