Twitterfone is an easy way to voice tweet from your phone. There are 3 steps to use the service (as shown on the homepage).
Step 1: Use your unique, swanky invitation code to sign up and create your FREE TwitterFone account.
Step2: Register your mobile or cell phone number and your Twitter account on TwitterFone.
Step 3: Send Tweets by dialing a local number and speaking your message to TwitterFone. Sweet!