Full, two-way interaction with Twitter over SMS is now available for everyone who uses O2, the largest mobile operator in the UK. There are no extra fees associated with Twittering over SMS on the 02 network—standard or in bundle rates apply for updating your account and receiving tweets over SMS is free so Tweet your heart out!
To Twitter over SMS with your iPhone or any other mobile, head over to your account settings and activate your device. The Twitter shortcode in the UK is 86444 if you want to save it in your address book. Twitter started with a strong focus on texting and Twitter continue to provide SMS access around the world.