The web service paradigm is a promising technology for developing applications in open, distributed and heterogeneous environments. The proliferation of this new technology has coincided with significant advances in the hardware and software capabilities of mobile devices. Due to the great benefits that come with the web service technology, such as interoperability, dynamic service discovery and reusability, there is a strong interest in making mobile devices capable of providing and consuming web services over wireless networks. This paper describes several scenarios of using web services in mobile devices and identifies their advantages, issues and challenges.