A system and method for identifying and establishing preferred modalities or channels for communications based on participants' preferences and capabilities is provided. In one approach, the system attempts to optimize the inferred or directly accessed preferences of a contactee given the accessed or inferred preferences, capabilities and goals of the contactor while keeping the rationale and context of the contactee private. Such optimization can be achieved using preferences and policies concerning handling the attempted contact based on a deterministic specification or through inferring context, content and task under uncertainty by employing decision-theoretic inferences to attempt to maximize the expected utility of the communication to the contactee. The methods may include a consideration of metadata within a standard schema that is transmitted along with a communication attempt, representing information about such attributes as the identity of the contactor, the task at hand, the overall context of the contactor, and the communication capabilities available to the contactor. The invocation of the communication service may be performed in a variety of ways, including single button invocations, and via a communication service that is more deeply integrated with other applications and functionalities. The service can also include automated rescheduling of communications based on a consideration of forecasts of availability of both the contactor and contactee.