How to Sign Up for Mobile Tweets

Third-party Applications
1. Go to the application store or marketplace on your phone and select a Twitter application. A few common, free applications are Twitter's mobile application, TweetDeck, Peep and Seesmic.
2. Download the phone application.
3. Open the application and log in using your Twitter username and password. The application immediately receives tweets from your friends and allows you to send mobile tweets.
Twitter SMS
4. Visit Twitter's website and find your country's Twitter short code. The code is 40404 in the United States.
5. Send a text to the Twitter short code with the message 'Start.' Twitter sends a text message back to you; reply with 'Signup.' This creates a new account.
6. Select a username. It must be unique and contain 15 characters or less. Reply to Twitter with that username. Twitter sends confirmation once the username is accepted.
7. Choose a password. Your account is set up and you can begin sending mobile tweets via SMS.
8. Send a tweet by texting the message to your short code.