The system of Classes of Service (COS) helps defining rights for one or another extension in the PBX or Centrex systems. For example, few groups require more space for storing voice messages, while other need the redirection of calls to cell phones, the third does not have to make calls outside of the office network. With the help of this system one can change and configure settings.
Major trends are changing the global telecommunications landscape. Voice traffic is rapidly migrating from large integrated international exchange carriers to more narrowly focused regional providers. This change is driving increasing demand for specializ