Twitter turned on the ability to share a photo on Twitter by attaching it to the an SMS text message.

Share a photo via text message

Note that this feature is, however, dependent on support and cooperation by mobile carriers. In the U.S., AT&T, Verizon Wireless and Cellular South support sending photos to Twitter via SMS.

Instructions for sending a photo to Twitter via SMS is found here:

How to Tweet a Picture via MMS

The Short Code or Long Code needed to send these photo Tweets is found here:

How To Find Your Twitter Short Code or Long Code