The CIX is a system that has been sold for nearly 10 years so programming it via a proprietary software was not uncommon in those days.
I agree regarding the proprietary software, but the CIX line has been around longer then 10 years. The CTX was released in 2002, and the version 3.0, renamed CIX was released in 2005.
I followed the link below barster and I see logos for a bunch of systems that used or still use software for programming, Avaya, NEC (DSX), Panasonic...
Also, by the way, the Network eManager is NOT required to program a CIX. My first CTX-28 I programmed completely by a 20 button phone. Back in the early versions of CTX the Ethernet NIC was optional. Network eManager is a programming aid, not a requirement, because programming through the phone is a pain.
While they don't provide a public link, Toshiba doesn't restrict the software to only Toshiba techs. They even pre-install it on a customer's MAS and Virtual IPEdge. They could have easily restricted the software to Toshiba techs through licenses if they wanted to (or a dongle like the older DK Admin)