隔空喊话

gé kōng hǎn huà

to converse with sb by shouting from some distance away

(fig.) to say sth intended for the ears of sb who is not in one's presence (often, by making a public statement or by posting online)

to separate

kōng

empty

hǎn

to yell

huà

old variant of 話|话[hua4]