“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.
COMTALK delivers DID/DDI numbers & termination in Denmark (but also most of the world) We offer SIP and are also MVNO, which means low cost calls to the Danish Celluar networks