Why do I see an “Unstable Network” message during calls?

An “Unstable Network” notification may appear during calls to inform you about the status of your cellular network connection. Connectivity issues may cause voices to fade in or out, audio silence, echoing or even dropped calls. These issues can be caused by many variables including inadequate coverage, quality of signal, interference, network congestion and potential network failures. If you see these messages often, we recommend that you switch to a Wi-Fi network whenever possible.