UC interoperability in a more heterogeneous world

Standard protocols like H.323 and SIP are supported by most modern UC systems so in theory products from different vendors can be installed and replaced as needed. Backend systems can interconnect and client devices, including IP handsets, aren't tied down to any type of IP-PABX.

Of course, I say "in theory" because your mileage may vary when it comes to UC interoperability. I can think of for the moment one UC vendor - and a relatively young one at that - whose handsets only worked with its backend systems. So during it's true UC today is more open than the telephony is yesteryear, it's truly doesn't have to be. There are some good examples of modern VoIP (Voice over Internet Protocol) systems that are in essence closed and proprietary.

Nowadays, a vendor would have to put forward a pretty compelling case for a closed system. As a matter of fact, the use of closed systems in business is most likely to stem from the use by employees of consumer VoIP products like Skype.