startEchoTest
Starts an echo test to evaluate the quality of the audio and the network connectivity.
This method runs a test that checks the outgoing audio quality and the overall connection stability, helping the user to determine if their device and network setup can support an acceptable call quality. The results of the test are returned through a RainbowListener, which provides the CallQuality object with the audio and video quality levels.
Parameters
listener
A RainbowListener that receives the CallQuality results upon test completion, or an error if the test fails.