New iOS 13 VoIP rules will affect how WhatsApp, Facebook Messenger, and other messaging apps work (via The Information—hard paywall).
iOS 13 VoIP
Apps that use Apple’s PushKit VoIP API to let users place and receive calls over the internet will be restricted to protect iPhone customer privacy. Currently, these apps can run in the background even when they aren’t in use. This helps them connect quicker but also do unwanted background tasks like collecting user data.
A Facebook spokesperson said:
The changes to the upcoming iOS releases are not insignificant, but we are in conversations with Apple on how best to address. To be clear—we are using the PushKit VoIP API to deliver a world-class, private messaging experience, not for the purpose of collecting data.
Of course, Facebook and privacy mix like oil and water, and former head of App Store review Phillip Shoemaker said:
Messenger can still use [VoIP background] mode, and does. What they do in the background, whether it be accept calls, listen in all the time or update the content of the main app, it’s all unclear to Apple, but could be happening.
Further Reading:
[Apple Banned Facebook App That Spied on Kids as Young as 13]