“Extension” - is the extension of the telephone line (PBX) or the Centrex system. It works as an association and allows calling to certain telephone sets without the necessity of dialing the telephone number, but only by dialing a short combination of digits, reaching the desired subscriber.
The Center of the System Administration was founded in 2001, in order to satisfy the needs for IT services of small-to-medium scale organizations by providing Open Source Software solutions.