The UX5000/sl1100/IPK-II/SV8100/SV9100 all use the same core program. The SV series has more of it with more options and better phones. The SV9100 is a grown up 8100, in that the licensing is different, newer phones, more software options. It comes in two sizes, the 9100S and 9100E. The "S" is a smaller cabinet with 3 card slots (the CPU uses the first one) and 48 ports. Software assurance is not required for it. The "E" is bigger with 6 card slots (CPU uses the first one). Both can be expanded. You can get them from a dealer or reseller.