Start-up Yoomba Thursday launched its namesake service that lets e-mailers place VoIP calls and exchange instant messages.

The year-old company positions its free, consumer-targeted service as an alternative to big portals, such as AOL, Google, Yahoo, and MSN, that offer free communications services, such as instant messaging, but only to registered users and only with other registered users, says Elad Hemar, Yoomba CEO.

In contrast, Yoomba operates a peer-to-peer service that lets any e-mail-address owner place a VoIP call or begin an IM session with any other e-mail address, whether or not the recipient also is a Yoomba user, Hemar says. Yoomba offers other features, such as presence -- letting users know who on their contact list is online -- and popularity -- resorting contact lists so those most often contacted rise to the top.

E-mailers become users by registering at Yoomba’s Web site. Unlike other services, Yoomba doesn’t require registrants to set up a logon and password. Instead they enter their e-mail address, and the registration process happens behind the scenes, where the company’s server links that e-mail address with their IP address, Hemar explains. The service places "call" and "chat" buttons in Outlook, Outlook Express, and major Web mail interfaces to contact people on the user’s contact list.

Leveraging a user’s existing e-mail contact list avoids what Hemar calls the "empty refrigerator" syndrome (you buy a new fridge and take it home, but it’s useless because it’s empty). Other services require users to populate new contact lists with other users who also use the service. Yoomba users can contact anyone with a known e-mail address.

With other services, “you install their application, you register, you choose a password, and at the end you get an empty application -- you have to work for the application. With Yoomba, it works for you,” Hemar says.

While images of e-mail spammers placing VoIP calls and sending IMs quickly come to mind, Hemar says the company is using the necessary back-end technology to prevent abuse of the service. “We will look at abnormal usage or IP addresses moving around” and instantly shut them down, he says.

Although the service targets consumers, Hemar says it probably will be attractive to small businesses as well, especially those that already use a Web mail address as their business e-mail address.