iOS SDK push notifications for chat messaging

We've developed an iOS app using the Rainbow iOS SDK. It successfully receives notifications for incoming voice/video calls even when the app is in the background.

But, if the app is not open/active, there is no notification received for chat messages, which means that the only way to know if a new message has been received is to open our app.

Can you please confirm that remote push notifications are not used for chat messaging and if this is the case, how can we alert our users that a new message has been received without them having to open the app?

Thanks