おんしんふつう· also いんしんふつう
break in contact; not hearing from; having no communication with
Noun
４年ねん以上いじょうも音信不通おんしんふつうだったんだよ。
I haven't heard a word from them in over four years.
もし音信不通おんしんふつうになったら警察けいさつに連絡れんらくしてね。
If I drop out of contact, let the police know, OK?