DLS provides consistent up time and prompt communication explaining issues in the rare event issues arise. We have the ability to immediately reach real and competent people in the United States for support issues; 99% of our support issues are resolved at the first tier level.
We like the flexibility of their PBX phones to make remote phone deployment easy with regular updates of the PBX software to add or tweak features that we need. It helps to have voicemail recordings sent to my email nearly instantly upon being left and having the ability to forward phone calls to cell phones, another extension, etc.
DLS makes it easy with a web-based administration of our PBX system.