Businesses could soon be able to target WhatsApp users following surprise changes to the messaging app's privacy policy.
The Facebook-owned message service, which is otherwise known for its end-to-end encryption and stringent privacy terms, assured users in a blog post Thursday that their phone numbers would not be made public and that messages would remain encrypted.
The changes are meant to "to test ways for people to communicate with businesses in the months ahead," the company wrote.
Practical applications could include receiving fraud notifications from your bank, or messages from airlines regarding flight delays, WhatsApp said.
"Our belief in the value of private communications is unshakeable, and we remain committed to giving you the fastest, simplest, and most reliable experience on WhatsApp," the company said.
Businesses could also end up using the service to send order, transaction and appointment information, as well as delivery updates and receipts, WhatsApp said.
While targeted marketing messages may end up being part of the service, the company said it did not want to overwhelm users.
"We do not want you to have a spammy experience," the company said.
But in a move that could spark controversy among privacy advocates, the company also announced it would start sharing account information within the "Facebook family of companies", including photo-sharing app Instagram and virtual reality technology company Oculus.
WhatsApp was bought by Facebook in 2014 in a deal worth 21.8 billion US dollars (£16.5 billion).
Account information will be used to "improve Facebook ads and products experiences", the policy statement said.
Phone numbers, for example, will be connected with Facebook's systems and used for targeted ads and friend suggestions, but would not be shared or sold to advertisers, WhatsApp said.
It will also track "basic metrics" such as how often people are using the app.
Existing WhatsApp users will have 30 days to accept the new privacy policy terms or stop using the service. Once accepted, users will have another 30 days to opt out of sharing their information with Facebook.