Missage is a couple of rings given by the caller to serve as a message/hint/clue to the called person. The called person expects the call and is not supposed to answer the call. It is popularly referred to as "giving a missed call". For eg, giving a missage so that the other party can store your number.
Missed call is a portmanteau of missed call and a message.
Rajath : Hey! I don't have your number.
You : Wait. I'll give you a missage.
Rajath : When are you coming to the party?
You : I'll be running late. I'll give you a missage when I reach there.