• There are two methods, (i) from your desktop or laptop or (ii) from your mobile phone.
(i) From Desktop: Log into your Twitter account and go to Setting -> Mobile. Now select your country and add your phone number. From the give list of Telecom operators (Carriers) select the one which you are having and click Activate phone.
In the next window you will get a number based on your network, sms 'Go' on that number and your phone will be added.
(ii) From Mobile: You can add your mobile via SMS. Send a text message with the word 'Start' on the number or short code based on your network (link is given below). It only works on selected networks, for example in India there are only four networks that support this service Airtel, Reliance, Videocon and TATA DOCOMO.
After sending 'Start' you will get reply from Twitter to message again with your username and after that with your password. At the last time Twitter will ask to send 'OK'. Send OK, and you're all set! You can now send tweets from your mobile to your Twitter account.
Note: Twitter dose not charge for this service but you may be charged from your telecom network on standard rates.
Use the commands given below to perform various functions:
• Sms ON to turn on all your authorized Twitter updates and notifications
• OFF, STOP, QUIT, END, CANCEL or UNSUBSCRIBE: turns ALL phone notifications off.
• FOLLOW [username]: to start following a specific user, as well as receive SMS.
• UNFOLLOW [username]: allows you to stop following a specific user.
• HELP - texting help or info to Twitter will bring up helpful tips.
For full list of commands click Here
You can use the numbers (short codes) for SMS given here