Personal Technology -- IM Services Offer Alternative to Phones, But Are No Bargains : "Instant-messaging services with voice calling have been around since the late '90s, but the sound quality was poor, and most customers could only text message or call people with the same service.
That is changing. Google recently launched Google Talk, a call service integrated into its messaging service. And Yahoo and Microsoft have announced plans for next year to have users trade messages and eventually conduct voice conversations. The two companies also recently released versions of their services that aimed to improve voice quality and offer new features like free voicemail."