When using Twitter on your phone via SMS, following a new user is the same as turning updates ON for a user. On the flip side, turning updates OFF for a user makes sure you will no longer get their Tweets via text but doesn't unfollow them. They will still appear in your web profile's following list. (There is no way to fully unfollow or block a user via SMS. Go online to your web profile in order to do this.)
For instance, if you'd like to follow @Oprah and get her Tweets delivered to your phone, send a message to your Twitter code with the command 'FOLLOW username', like so: FOLLOW Oprah
If you do not follow @Oprah already, this command adds her to the list of people you follow and sends all of her Tweets to your mobile phone. If you already follow her, the command will simply make sure you get her Tweets on your mobile.
When you want to stop seeing Oprah's Tweets, simply turn updates off for her by sending the commands "LEAVE username" or "OFF username" to your Twitter code, like so: LEAVE Oprah
You will no longer get her updates on her phone. However, you will still be following her on your web profile. This means that if she sends you a direct message, you will receive it. You'll need to log on to your web profile on www.twitter.com to fully remove her from your following list.
Closed for comments