WIP330

This can be a number of things which we can look at in turn.

1. Make sure you are using the latest firmware version. Many problems are solved by a simple upgrade.

2. Make sure your network or internet connection is not overloaded. This is not very likely with most modern broadband accounts but is possible if you are running Bittorrent clients, streaming video or using other bandwidth hungry applications or devices at once. Many routers now have QOS (Quality of Service) or other traffic shaping features built in which you can use to give priority to VOIP. Otherwise turn off these bandwidth gobblers before using the phone. Try using the WIP330 on another network. If they call quality is better then the problem is with your own network connection.
Here is an Online VOIP Bandwidth Calculator you can use to check your consumption.

3. Check your codecs. There are a variety of different codecs, sometimes called Payloads, which can be used in combination to reproduce the voice call quality. These vary in quality and in the amount of bandwidth they use. Different VOIP providers may favour different codecs. Check which ones they use and set the WIP330 to the nearest one using the GUI (SIP Settings/SDP Settings).

Codec Settings