Sound notification on phone

Why some cameras send to phone notification (sound one) and some not i got 3 cameras one ok other two stop send me Afther two years!!!

Hi @Vii. Are you able to Live View from the other cameras? Do their recordings show up in the Event History? What is the RSSI for these Cameras? I’m unsure of what type of phone you are using, but this Help Center article will have information on troubleshooting notifications on iPhone and Android.