“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.
IPness is a product of The Phone Company nv/sa, The Phone Company of Belgium was formed in 1996, and has been serving large international carriers with high-tech innovative solutions and special value-added services.