&gt; Here&#x27;s irony for you: basic text messaging is almost free to the carriers, because it actually happens on the cellular protocol&#x27;s control channel.<p>The airtime is basically free (although, if send&#x2F;receive volume is high, this ends up with more of the control messages sent than would have been with an idle phone), but routing and storing the messages in transit isn&#x27;t.  Also, a lot of carriers have contracted out their SMS systems and are paying their contractors per message.  Everybody charges everyone else for SMS between carriers as well.