Call waiting notification on iphone!

Hi all,

When we are making a call to someone, if he/she is on another call, why does not iphone shows “call waiting” on our screen.

This facility is available on android phones.

Further to my studies on this I found that it is due to an apple’s security feature 🧐 but I still do not understand how this could affect phone’s security 🤷🏻‍♂️😅

Any smart guy to solve this???