Hi @minglegs. Both the the Ring Doorbell and the Ring Chime are connected to the Ring app via your wifi network, and that’s how they communicate with each other. There will be a slight delay after someone rings the Doorbell before the notification will sound on the Chime. If you’re experiencing significant delays in notifications, I’d recommend checking the RSSI on your Doorbell as well as verifying the wifi strength on your mobile phone to reduce any excessive delays.