Can anyone explain the talking dog? *Spoilers*

Was the dog's speaker always controlled by a future version of Alice?

There doesn't seem to be anything to suggest what time period the film takes place in. I'm under the impression it is set in some unspecified time in the future, and at first I thought the box on the dog had some basic AI simulation to help with the girls grief from the death of her mom, sort of like in the Black Mirror episode "Be Right Back."

But when Future Alice switches places with Past Alice she controls it with her phone. Was this always the case? Had a future version of Alice been lurking about for some time and been using the speaker to attempt to influence the actions of Past Alice? If so, why was the speaker attached to the dog to begin with? Perhaps it was always just a fantasy she had and had been controlling the voice herself, until Future Alice began sending messages through it.

Anyway I quite liked the film. Very unsettling and odd.