For the most part, Gankutsuou is set in Paris in the year 5053. Technological advancements shown in the series include:
Space travel and moon colonisation
Danglars' communication with Michelle, his assistant, over a wireless connection
Noirtier de Villefort's prosthetic arm
The pen inside Noirtier's arm, which auto-writes and which is used to access his memories
Lucien Debray's use of headsets to access government records through a VR application
The Count's pocketwatch, which is revealed to be a bugging device
With this taken into account, I was surprised to realise that the main characters never seem to use cell phones or email, even in situations such as:
Albert's failed attempted to see Eugénie after her engagement to Andrea Cavalcanti
Eugénie's thwarted attempt to see Albert after the Morcerf scandal breaks out
Eugénie's failed attempts to contact Franz while he was in Marseilles (although it is also possible that Franz intentionally made himself unreachable)
Do cell phones and email exist in the world of Gankutsuou? If they do, why do the characters not use them? Or are the technological advancements in Gankutsuou just constructed so that the original social structure of the novel is not changed?