According to its live Twitter feed iPhone carrier O2 is suffering problems with its Pay Monthly internet access and MMS services.

The Twitter feed (@02) states: "We're having a problem with Pay Monthly internet access, this will affect MMS too. Sorry - we're working to fix this ASAP."

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O2 is Apple's exclusive carrier in the UK for the iPhone, and will soon be the same for the Palm Pre.

There are seven O2 Pay Monthly iPhone tariffs to choose from, costing £29.38 (75 mins talk, 125 texts), £34.26 (600 mins talk, 500 texts), £44.05 (1,200 mins talk, 500 texts), and £73.41 (3,000 mins talk, 500 texts), on an 18-month contract and £34.26, £44.05 and £73.41 on a 24-month contract. (All tariffs include unlimited UK data and Wi-Fi.)