Messaging apps are proving enormously popular across the globe; WhatsApp CEO Jan Koum recently solidified that point by claiming that his company’s service has grown even bigger than Twitter. If that wasn’t enough to give mobile operators pause, a new study from Informa may do the job. The research, conducted on behalf of the Financial Times, concludes that chat apps have overtaken traditional SMS in terms of message volume. By the end of 2012, more messages were being sent with WhatsApp, Kik, and manufacturer-driven solutions like iMessage and BBM compared with regular texting. SMS has long been a massive source of revenue in the mobile industry, so the consumer push towards free-to-use replacements is a worrying development for carriers. EU Commission VP Neelie Kroes was quick to highlight the finding.