“Phoney” is an adjective meaning false, and it has no connection to “phone”. The noun is phoniness (falsedad).
If a mortal is phoney that person is not sincere or insincere (insincero). So a person who is being a phoney is showing phoniness, pretending to be something which is false, a sham, or pretentious (pretencioso).
Some examples:
- By offering Ukraine very old tanks, Mr. Sanchez, the Spanish Prime Minister, perhaps thought that he was offering Ukraine something wonderful. It turns out (resulta que…) that they are, in practical terms, useless. So he is guilty of phoniness: he was being phoney.
- There is something phoney (algo falso) about his offer.
- Many politicians have the same phoney smile (…la misma sonrisa falsa).
- Mr. Trump´s driving licence is phoney.
So phoniness is in abundant supply because mortals often prefer phoney behaviour.