The publisher runs competitions, voting and horoscopes, via premium-rate lines and mobile phone messaging, for readers of its national newspapers, which also include the Daily Star, and celebrity magazines OK! and New.
Readers can also send in marriage or new baby pictures via MMS to be printed in the Daily Express' Saturday magazine.
Opera is providing content, campaign management, infrastructure delivery and billing, working on a revenue-share basis with Northern & Shell. It provides one point of contact for all the interactive services.
Leila Palmer, telephony and new business controller at Northern & Shell, said: "Our newspapers and celebrity magazines play an important part in our readers' lives. As they are also highly mobile literate, SMS, MMS and interactive voice recognition services are the perfect tool to increase their engagement with their favourite publications."
Opera's other clients include GMTV, ITV, Mersey TV, Endemol, BT and Virgin Mobile.
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