The Snapshot competition is open to anyone with an MMS-enabled phone on any major UK network. Participants are being asked to snap a photo based on a theme, such as 'the best part of your day', and send it to 07974 457627.
The photos will be published in the online Snapshot gallery. Visitors can browse other entries in the 'inspire me' section, and register to receive regular email updates of new challenges and the latest Snapshot news. A viral element also enables people to forward images to their friends.
Users can vote online for the winners who will pick up a prize from Red Letter Days.
Snapshot follows Orange's Expressionist campaign of last years, which encouraged the public to send in pictures of facial expressions.
Orange e-marketing manager Alex Snape said: "Expressionist was about getting the public to send their first photo message. Snapshot takes this to the next level - it will awaken users' creative spirit and get them using their cameras in a more innovative way."
Mobile marketing agency Enpocket is responsible for the mobile delivery, with in-bound photo messages delivered straight to Snapshot web site.
Agencies Fullsix and Poke are jointly responsible for creating the Snapshot site, as well as the emails, banners and creative promoting the campaign.