Second Life is to extend its voice-based services into the real world with the ability to make calls and send text messages into and out of the virtual world.

Linden Lab, the creator of Second Life, has revealed its roadmap for the remainder of this year and into 2010, highlighting the evolution of its voice service, which has already racked up over 15 billion minutes since its introduction, the firm said.

Over half of Second Life subscribers use voice as part of their everyday in-world experience, according to the company, primarily for education, business meetings, simulations, training and casual conversation.

"The rapid adoption of voice services over the last 18 months demonstrates that we have a significant opportunity to evolve our offering, while further strengthening our business model," said Joe Miller, vice president of platform and technology development at Linden Lab.

"From its inception, the value of Second Life from a user experience and revenue perspective has been tied primarily to the Second Life viewer. One of our larger strategic goals is to extend that value beyond the virtual world, giving our users the ability to fluidly integrate Second Life into their everyday lives."

The first addition to the VoIP platform, currently under beta testing, is AvaLine, which will assign residents with a Second Life 'phone number' which can be dialled directly from an outside landline, mobile phone or VoIP application.

This will be followed by SLim, a one-to-one voice and text application that allows Second Life users to interact directly with each other without needing to have the viewer open.

In the latter half of 2009, the company expects to release Voice Fonts, allowing an avatar to substitute their own normal voice with that of another. Linden Lab gave the examples of a French woman, a sports announcer or an elf.

Also due this year is outgoing text messaging and client-side recording, which will enable residents to record voice conversations for playback later. Next year, Linden Lab will extend these services to include conference calls, group chats and browser-based voice applets.

Details about the business model and pricing for the new services are not yet available, and will be announced once the beta testing is complete and the full service goes live.