Facebook's $19 billion purchase of WhatsApp may not be signed and sealed just yet, as privacy advocates have asked the Federal Trade Commission to put the deal on hold.According to Reuters, some are skeptical of the acquisition and want Facebook to be more transparent about how they intend to use WhatsApp's messaging service. Facebook already has a popular mobile messaging app, but WhatsApp has 450 million users worldwide.WhatsApp has also committed themselves to not gather data from its users to use in advertising, something Facebook does freely. If Facebook's purchase is completed, WhatsApp's commitment will likely end.Although it is not entirely clear, Facebook has one obvious purpose for acquiring a messaging service used worldwide. Facebook is a leading backer of Internet.org, a project that aims to provide an Internet signal for the five billion people in the world without one. Even with a slight signal, WhatsApp could provide means of communication to every person on the planet.Facebook also purchased a drone-making company, which is more than likely to aid the Internet.org project."As we have said repeatedly, WhatsApp will operate as a separate company and will honor its commitments to privacy and security," Facebook said in a statement.The group of privacy advocates, the Electronic Privacy Information Center, filed with both the FTC and the Center for Digital Democracy, both non-profits. Neither commented on the filing.According to Bloomberg News, the complaint centered around the fact that Facebook freely uses user data for advertising, a practice WhatsApp strictly avoids."Facebook routinely makes use of user information for advertising purposes and has made clear that it intends to incorporate the data of WhatsApp users into the user profiling business model," the document read. "The proposed acquisition will therefore violate WhatsApp users' understanding of their exposure to online advertising and constitutes an unfair and deceptive trade practice, subject to investigation by the Federal Trade Commission."But Facebook maintains they do not intend to change anything about WhatsApp."Facebook's goal is to bring more connectivity and utility to the world by delivering core Internet services efficiently and affordably - this partnership will help make that happen," the social network's statement read.