In early January, tech billionaire Elon Musk’s two-word tweet, ‘use Signal’, sent online folks into a hyperdrive—people rushed to download a messenger app that has been around for a few years, but till then was used by a small, niche set. In the debate over privacy that was touched off by WhatsApp’s new policy update over sharing certain data with its parent Facebook, Musk evidently provided the nudge for those considering a shift to another messenger service.