O2 UK has begun to roll out the fastest variant of 3G currently available - DC-HSPA, dual-cell high-speed packet access, which may see some mobile download speeds double. Whilst it's not 4G, it is an improvement over the current 3G connectivity.
The variant of DC-HSPA that O2 UK is providing has a theoretical maximum of 42Mbps, double that of the HSPA+ version of 3G that is currently more widespread.
A spokesman for O2 has said that 'major UK cities' will be the first to benefit from the roll out, with London, Manchester and Birmingham being the likely candidates.
Support for DC-HSPA has already been included in the UK version of the new iPad, while Nokia has added DC-HSPA to the European Lumia 900 smartphones.
Three has said that it is planning to roll out the 42Mbps variant of DC-HSPA this summer, and Everything Everywhere, the company responsible for Orange and T-Mobile, is aiming to roll out DC-HSPA in the fourth quarter this year.
Vodafone does not currently have any plans to upgrade to the 42Mbps variant of DC-HSPA. The release of 4G is dependent on a new spectrum, so it is on hold until 2013 at least.