Three main things attribute to a bad call quality.
The first is a poor or mediocre internet connection. If the app is used on a mobile phone and cellular, hotspot, or public Wi-Fi signal that's not in favorable conditions, choppy and dropped calls may be experienced.
The second is if the customer or client is also calling from a place with poor connection.
The last thing is if RingCentral services quality drops during a network spike or server congestion, thus creates latency and the inaudible poor voice communications.