Various factors can impact call quality on the application such as dropped calls, static, cutting in and out. Quality is reliant on individual factors such as network connections, wireless networks, location, etc.
For call quality issues, these will need to be analyzed and troubleshot on an individual basis as each device and network play unique factors to quality of service.
The officeXtend client has a helpful troubleshooting tool that can be utilized to expedite the troubleshooting efforts. When a user is on a call, they can press the information icon in the upper right corner of the in-call screen and be able to view the data of that call: Signal strength (in bars), jitter, and so on.
To enable logging: