I disagree, and I'll tell you why. If a Kalashtar were NOT always listening, then how in the world would the Telepathic Sensitivity feat work? I think a better analogy would not be the telephone, but rather a telephone switchboard. It knows all the calls are there, but at first, can only plug into one call at a time (the single cord with connections at both ends). It hears the rings, but can only connect to the ones directed at his/her switchboard.
What the Group Mind feat is doing, on the other hand, is splicing a bunch of these cords together and adding connectors to each of the many ends, which are plugged into all of the kalashtar's ally's communication ports, allowing each of the allies to speak to each other ally, using the kalashtar as the conduit, rather than speaking to the Kalashtar directly.
What the Group Mind feat is doing, on the other hand, is splicing a bunch of these cords together and adding connectors to each of the many ends, which are plugged into all of the kalashtar's ally's communication ports, allowing each of the allies to speak to each other ally, using the kalashtar as the conduit, rather than speaking to the Kalashtar directly.