Facebook starts to integrate with its WhatsApp messaging app8
Despite comments made after Facebook announced the acquisition of WhatsApp that both would continue to operate as standalone applications, there is speculation that both companies are working on other ways to integrate both sites. The goal for Facebook is to drive more traffic to both apps and book more ad revenue for itself.
With voice calls coming to the iOS and Android versions of WhatsApp, there is some gossip about Facebook's interest in employing this technology for its own app. Despite all the talk about both apps remaining independent, you can expect more integration between Facebook and WhatsApp in the future.
source: Geektime via Reddit, AndroidAuthority