All new and upgrading customers as of the iPhone 4’s June 24 launch will have plans with a fixed amount of data that will require Bolt-On extensions to extend. Customers will have to pay either £5 for each extra 500MB block of data or £10 for another 1GB.
The carrier has also set some of the lowest average caps in the UK. Two-year contract plans between £25 per month and £35 per month stop at 500MB before they need Bolt-On data. It isn’t until £40 that customers get 750MB of data.
Read more at electronista: http://www.electronista.com/articles/10/06/10/o2.makes.500mb.cap.common.for.most.sma