I have saved my wife's number as 'darling' in my mobile phone. So when she calls me I can see the screen and know that darling is calling me. But I don't know the name by which she has saved my name...it could be honey, hubby, dumbo, jumbo..who knows..
so an app which can tell this - is what helps.
with that app, my phone will say - 'darling is calling jumbo' and not just 'darling is calling'
Note: this is just an illustration to share the idea. I have used some fictitious words like darling, honey etc ;)