The best feature of pump is its simplicity as it has all features which are required by any software development team. It doesn't have much customization but we can customize some things according to our need. This makes easy for us to use this tool in our projects. There is nothing that I dislike about this product. If you want an easy way to test sip softphones then go with pump. We used it while developing one of my client's project and now i am using it at home. As compared to other products available in market, pump offers more flexibility than others. It helps me to develop my client's applications easily without worrying over their problems like compatibility issues etc.