问题
We are using the Sinch SDK to enable mobile app (android) to browser (web app) calling. Calls are establishing all OK but we are having issues with call quality being very variable. We are using 3 and 4G for mobile connectivity.
We have an external sound card on our android device since we are in a noisy environment and need external amplification and a microphone closer to the driver.
Calls from the web browser (office based) to the mobile app (in vehicle) are of excellent quality but calls from the mobile app to the web browser are severely distorted to the point that they are unintelligible.
On the basis that the incoming audio (to the mobile app) is excellent the network connectivity must be OK - i think?
What could be the cause of this?
Thanks
来源：https://stackoverflow.com/questions/31278922/why-is-the-sinch-call-quality-from-mobile-app-to-browser-very-poor