The first step to improve call quality is to use an Ethernet connection (CAT5e or CAT6). Using Quality of Service (QoS) will help guarantee call quality. It can help minimize voice latency and prioritize bandwidth to your calls.
Without getting into the technical details, voice latency can cause interrupted calls. However, with Quality of Service, you will have sufficient bandwidth allocated to your voice calls.
If you are a small business owner, you probably won’t need to use QoS. It’s more likely to be used by organizations that handle high concurrent call volumes.