“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.
uVOIPit is a retail international VoIP service and wholesale VoIP termination business. It started in February 2010, and LLC licensed in April 2010. Website: http://www.uvoipit.com