I read this short story about thirty years ago, more or less. There's a colony of people who are cut off from the main body of people. There are enemies between... and everybody communicates by telepathy. But nobody can get in touch with the main group, except that this little girl can hear the voices of many other people. Her adult companions recognize that she is hearing from the main group, so they have her speak telepathically to them. She can do so; none of the others with her has the power to reach with telepathy the main group. In the end, she brings help, and all recognize the sheer enormity of her telepathic gift.
I tried to describe this story as best i could, and I remember it was great.