“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.
Code-A is Telecode Communications Inc. billing for collecting CDRs and Softswitch management via TXT files, SNMP and DBMS. Code-A has its own framework designed to calculate every call and not to miss any.