The notification "The call service is ready" is coded in our React Native SDK and Flutter SDK.
If you use our React Native SDK or Flutter SDK, please take a look at the implementation of WebRTC and WebRTCCallService.java so you can remove unnecessary push notification functionality.
You may check these paths depending on the SDK:
Please refer to the corresponding documentation:
Also, you can change the text of the notification for both SDKs in /android/src/main/res/values/strings.xml.
And change the logo by replacing the files ic_call_service_large.png and ic_call_service_small.png in the following folder: