Interoperability is the ability to make systems and organizations work together; or in the video sense, the ability for two video conferencing systems to connect with each other. Systems that operate on the same protocol are interoperable with each other while systems on different protocols are unable to connect. For example, a Polycom video conferencing system can connect with a Cisco video conferencing system because they are both using H.323. However, a Polycom or Cisco system cannot connect with Skype or Facetime because neither of these uses H.323. There are numerous cloud based and hardware solutions that enable interoperability between otherwise disparate systems.