Google stepped up its attack on the telecommunications industry on Thursday with a free service called Google Voice that, if successful, could chip away at the revenue of companies big and small, like eBay, which owns Skype, telephone companies and a string of technology start-up firms.

Google Voice is an expanded version of a service previously known as GrandCentral, a start-up that Google acquired 20 months ago. It is intended to simplify the way people handle phone calls, voice mail and text messages. The service will initially be made available only to existing GrandCentral subscribers; Google says the general public will be able to use it in the coming weeks.