A new web-activated telephony service, jajah.com, has seen the light of day. Jajah is instant voice over IP that doesn’t require software downloads, installation, headsets, or special hardware as does its competitors Skype and Vonage.

The target user is a person who doesn’t have the time or skills to get started with any of the existing VoIP services.

“It’s so simple my grandma can use it,” says Jajah co-founder Roman Scharf.

To get started you type in your phone number and the number you want to call on Jajah’s web page. Then click the call button and the service bridges the phones. It works, I just tested it on my brother in Sweden.

Regardless of phone company or plan, Jajah allows long distance and international calls - landline or mobile - to most numbers for less than 2 cents a minute (European cell phones excluded). There’s no monthly fee, no registration fee, no prepayment. You get 5 free minutes to experience the service. You pay after you called, with for instance credit card or Paypal.

If you’re a Firefox user, there is a Jajah extension that automatically detects and highlights phone numbers on web pages. When clicked, Jajah initiates a phone call from your phone to the desired destination. Or, you can enter phone numbers directly in the toolbar.

The Jajah calling service is also integrated in Plaxo, an online address book, allowing members to initiate calls by clicking on any phone number in their address book.

The company has plans on enabling conference calls. And they will launch a service that will let users initiate calls from mobile browsers this fall, Roman Scharf and his team are already testing the software on their own cell phones.

“We hope to have one million paying users by the end of this year,” says Roman Scharf. Compare that to Skype having 200 million registered users and 1.5 million paying.