A system registers participant information and inter-participant relationship information, and then, at variable times, selects two or more participants with a pre-existing relationship and attempts to establish a communication link between them. The identities of the selected participants are withheld from at least one of the participants (and potentially from all of the participants), so the call is a partial surprise (i.e., the participant may know the set of possible people from whom the call could be, but does not know exactly which person or people are calling until he answers the call). A number of applications are described and claimed.