TwitterFone is a free service that lets you update your Twitter feed using your voice from any mobile or cell phone. You call it, speak up your tweet, and hang up. Then a short while later, your tweet will be posted on Twitter.

Twitterfone launched in May Twitter to let users post new messages by calling a phone number and talk about what they mean. The service then converts the message text and posts to your account Twitter with a link to audio file. Here is a test message, I created at the launch. The service is a great way to leave a quick Twitter message when you are away from your computer and only have access to a phone - the service offers local numbers in 19 countries and is growing steadily. The company says 20000 people have registered for the service since its launch.

Today Twitterfone begin Twitter convert your audio messages, too, giving users an audio interface for the service. Today, if you call Twitterfone the service offers to register a new message, listen to messages from your friends, and respond to messages public or private. Users can listen to the first ten messages.

For now, only English is supported, but is a Japanese side. The service is free and will remain so for the foreseeable future. If you are a Twitterer, you’re gonna love this.