Call logs include the date when you have called, the telephone number to which you called and the duration of the conversation. You can also add notes to the call log. You can review call logs by the telephone.
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.