Hey,
Welcome to the forum.
Ways of improving voice quality:
- Make sure you are using QoS on your router.
- Separate voice and data on to different networks/ISP connections
- Change codec in use to ITU G.711 - 64 Kbps, sample-based Also known as alaw/ulaw or higher
- Don't use cheap kit!
- Switch to a business specific provider.
Who are you with at the moment out of interest?