When you're on a business trip, running errands or on vacation, you probably don't have the same access to a computer as you do during the workday. But if you tweet on the go or like to keep up with your Twitter followers outside of work, mobile access to Twitter is essential. Here's how you can receive direct messages and @ replies directly to your phone, plus a rundown of five Twitter text commands you can use to communicate with your followers when you're on the go. How to receive Direct Messages and @ replies as text messages.From a computer: Log in to your twitter account and choose "Settings" from the drop-down menu next to your username. Choose "Mobile" to add your phone number, which will allow you to send updates to Twitter via your mobile phone and receive messages.After you've entered your phone number, click "Start" to verify your phone. You will be asked to send a message to Twitter's U.S. target="_new">mobile number, 40404. After you receive a text message saying your phone has been verified, revisit your mobile settings page on Twitter.com to update your preferences.[Twitter Tips: 4 Ways to Revisit Your Twitter "Firsts"]\nHere, you can choose whether you want to let others find you by your phone number. You can also choose whether to receive Tweets from people you've enabled for mobile notifications, direct messages, mentions and replies. You can also choose to turn updates off during a specific window of time, such as 11 p.m. to 6 a.m. when you're sleeping. From your mobile phone: Text the phrase "set mentions on" to 40404 to activate these notifications. You'll receive a text message anytime someone mentions your name in a tweet.[5 Free Tools to Spring Clean Your Twitter Account]Five essential Twitter text commands.To enable any of the following commands, text them to 40404, or your country's Twitter short code. Note that you need to use capital letters where shown.OFF: Text this command if you want to stop receiving SMS notifications for updates except direct messages. Send STOP to turn off direct messages, too.ON username: This turns on notifications for a specific person. You do not need to use an @ before the username. Similarly, to turn off notifications for a specific person, text "OFF username".D username + message: Use this command to send a direct message to a user.SET LOCATION placename: This updates the location field in your profile. For example, texting "SET LOCATION Boston" will change your current location to Boston.STATS: Text this command if you want a return text with your number of followers, how many people you're following and your bio information. Kristin Burnham covers Consumer Technology, SaaS, Social Networking and Web 2.0 for CIO.com. Follow Kristin on Twitter @kmburnham. Follow everything from CIO.com on Twitter @CIOonline. Email Kristin at email@example.com.