HALIFAX - EastLink is investing $4.2 million to upgrade its network around the southernmost reaches of Nova Scotia and will soon launch local telephone service in Yarmouth and its surrounding communities. The upgrade to EastLink’s digital network will also enhance the quality of existing EastLink services in the Yarmouth area, said the company. Upgrade construction in Yarmouth began in November 2006 and will be completed by Summer 2007. EastLink Telephone service is available for $20 per month and customers choosing to switch to can enjoy free installation and are able to keep their existing phone number, jacks and directory listing....