With recent advances in portable computers and wireless networks, it is now feasible to provide sophisticated IT support for a range of mobile workers in areas such as the police, ambulance services and the utilities industries. However, to date, such support has been limited to providing remote access to central facilities such as e-mail and databases. This paper focuses on extending this level of support to include collaborative applications requiring multimedia communications. Such applications make considerable demands on the underlying systems infrastructure. More specifically, the paper discusses the role of such collaborative multimedia applications in supporting field workers in the electricity industry. A prototype conferencing application is described which enables field engineers to jointly view and annotate network diagrams and maps produced by a Geographical Information System. Voice communications is also provided to enable discussions to take place. The underlying distributed systems platform is also presented. The application has been successfully demonstrated over GSM.