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](https://community.ring.com/t/how-it-works-your-ring-device-rssi-good-vs-poor/229#M4) on your Doorbell as well as verifying the [wifi strength](https://support.ring.com/hc/en-us/articles/360020638172-Test-Your-Wifi-Connections) on your mobile phone to reduce any excessive delays.