When you encounter the sound quality problem while using the phone, please do the following troubleshooting:
1. Try to change the curve of the phone handles of both the calling and called parties and then test
2. Check if the connection between the phone handle and the curve of both the calling and called parties is normal.
3. The sound quality problem occurs during the call, immediately switch from the handle mode to the hands-free mode or switch from the hands-free mode to the handle mode to check whether there is a problem with the sound quality.