In third-generation (3G) networks, third-party service developers will have access to the mobile network resources using open network interfaces, such as the 3rd Generation Partnership Project's (3GPP's) Open Service Access (OSA). The service platforms that offer these interfaces provide interoperability, third-party access, and ease of use, which goes beyond the capabilities of existing intelligent network technologies. OSA is usually implemented using CORBA* object middleware. To accommodate a broad community of developers and scenarios of deployment, middleware technologies other than CORBA should be supported as well. In this paper we discuss Web services, an emerging Extensible Markup Language (XML)-based middleware technology that is especially targeted at the Internet community. We describe the technical benefits of both Web services and CORBA in an OSA context and look at the main issues and possible solutions with respect to offering Web services-based access to the OSA interfaces. We also describe a prototype to validate our conclusions.