The name Comcast Corporation is generally associated with cable TV, but now the company is about to take a major leap into the local phone service industry. Comcast officials are announcing plans to offer Internet-based phone service. Existing Comcast broadband customers can sign up for unlimited local and domestic calls for just under 40 dollars a month. The package also includes caller ID, voice mail and call waiting. Digital Voice from Comcast will be competing with similar packages offered by Verizon and Vonage. Comcast says it plans to roll out the new service in 20 markets this year, and will likely be expanded nationwide by next year.