New York - Global messaging service WhatsApp says it will start sharing the phone numbers of its users with Facebook, its parent company. That means WhatsApp users could soon start seeing more targeted ads on Facebook — although not on the messaging service itself.

The move is a subtle but significant shift for WhatsApp, which has long promised to safeguard the privacy of more than 1 billion users around the world. WhatsApp is giving users a limited time to opt out of sharing their information with Facebook, although they must take the extra step of unchecking a box to do so. It also says Facebook won’t post phone numbers online or give them out to anyone.

But the giant social network has been looking for ways to make money from WhatsApp since it bought the service two years ago, in an eye-popping deal ultimately worth $21.8 billion. At the same time, Facebook has pledged not to interfere with a longstanding promise by WhatsApp’s co-founders to respect users’ privacy and keep ads off its messaging platform.

WhatsApp on Thursday offered a glimpse of its plans for turning on the money spigot, releasing new documents that describe the company’s privacy policy and the terms of service that users must agree to follow. The documents are the first revision of those policies since 2012, before Facebook acquired WhatsApp.... Read More: VIN