Better targeted ads and a lower cost per lead are what a business gets when every real customer interaction, not just what happens on a website, feeds back into Facebook's ad systems. A text reply or a delivered SMS is exactly that kind of interaction, and normally it never reaches Facebook at all, so the ad account keeps optimising against an incomplete picture of who's actually engaging.

Mobile Message can send it through Zapier instead. An Inbound SMS Received event can trigger a Send Lead Event action, so a customer who texts in for the first time is reported to Facebook as a lead the same way a form fill would be. A Delivery Status Updated event can trigger a Send Other Event or Send Funnel Event action, giving Facebook a record of SMS engagement to weigh alongside everything else it already knows about that audience, and a fuller signal to build the next campaign around.