My Raven screen is locked and somebody is calling me, but I cannot see who it is. Why does it happen?

This functionality is meant as a security measure. While your Raven is locked nobody will see who is calling you. Raven will still be ringing and the call can be answered by picking up the receiver.

If you want to change the lock settings please go to Settings > Security > Screen lock and select what kind of protection do you want to use. You can also disable the screen lock and next time you will see who is calling.