Context aware systems are a promising approach to facilitate daily-life activities. Concerning communication services, business users may be sometimes overloaded with work so that they become temporally unable to handle incoming communications. After having surveyed the challenges to build context-aware systems, we introduce here HEP, a system that recommends communication services to the caller based on the callee's context. HEP's main context source is the usage history of the different communication services as well as the users' calendars. It has been prototyped and tested at Orange Labs.