Whatsapp desktop knows if my phone is on

[garyhbutton]

I started using whatsapp desktop and dont fully understand how it works. After the initial pairing the desktop app can send messages on my behalf. If I turn off my phone it will stop sending messages. If I then turn on my phone but run no apps, it will continue to send messages. How does this communication work? Does iOS run something in the background?

[Tomte]

Of course iOS runs platform services in the background. Push notifications, in this example.

[garyhbutton]

I turned off push notifications for Whatsapp and the desktop app is still able to tell if my phone is on or not

[garyhbutton]

Note I am using a MacBook Pro and iPhone in this situation.