Comment by svpk

1. I'm not an iOS dev, but I know they have a specific framework for doing calls (CallKit I think), so you'd be using specific APIs that allow for a persistent connection for that purpose. Probably something similar for downloads. But generally iOS kills apps running in the background after a while so there's no way to persist an open connection indefinitely.

2. To be clear it's my understanding that the notifications weren't exfiltrated off the device. The notifications are stored in a database on the device that iPhone and can only be accessed by unlocking the phone. So I wouldn't call it a backdoor. Both Android and iOS retain notifications in a database, in Android you can disable it, I don't know about iOS.