I'm sure they have call display in the future, just Anthemys didn't look at it assuming the caller to be Tal or one of her models since no one else ever calls her. ( She likes it that way. )
Bretnon Falstoph Perius Tallifens Monteblanc LV, generally just called Perius, grandfather of Tal and Anthemys, current head of the Monteblanc household. He was mentioned in the very first arc, but not by name. He's the one keeping tabs on Tal and Anthemys - their father is happier to assume the worst and complain than to actually collect facts.
Perius is ( currently? Unknown on dead ancestors ) the only one in the family who sprinkles French into his conversations, because as long as he knows the language he might as well. It's not like he gets to use it anywhere else. However, his first language - like everybody's - is Standard.
The Monteblancs are colour-coded because they all look alike ( careful breeding, not cloning. ) Everybody else in the series is colour-coded because I trained on superheroes and How To Make Your Hero's Costume Identifiable Even If You Turned Him Into A Pirate Or Something. Start from the beginning of this arc. Start from the beginning.