English: Can you set your phone on airplane mode?
French: Pouvez-vous régler votre téléphone en mode avion?
"Telephone" in French is simply "téléphone" (m). A "cell phone/cellular telephone" is "téléphone cellulaire" in Canadian French. European French speakers tend to use "portable" (m).
In a flight attendant's context, it's clear when you ask "pouvez-vous régler votre téléphone en mode avion" that you're referring to the passenger's cell phone, as opposed to their landline phone. Thus "téléphone" is usually enough. It's usually not necessary to specify "téléphone cellulaire."
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