Can't give a detailed description off the top of my head, but the IPKII has many more features than the DSX. More expensive, too. The biggest differences is that the DSX does not offer route selection, voip, or tel set add-on modules. It is watered down, but if you do not need a lot of features (though it has many), the DSX is the way to go. The best part is that the voice mail is very inexpensive and the telephones sets are nicer. The IPKII, however, is an incredible system feature-wise. It is extremely configurable and difficult to max out. In my opinion, it is closer to a PBX as far as hybrids go. You can do just about anything with it. The DSX does not require you to be a dealer. You can get it through GraybaR or ADI, the warranty is two years, the 22 button sets are only $99, the voice mail is just a compact flash card for $500/$800 (4/8 ports). It even has a built in auto attendant. The IPKII requires a dealership. IPKII also has WebPro, which is totally cool! So, it really depends on the application. The DSX is an awesome small business switch. The IPKII is highly configurable/expandable. You wouldn't have to worry about future customer requests.