You can purchase additional data bundles from Three, of course, or pay only for what you use, with rates starting at 1p per megabyte. And even if you stick within your free monthly allowance, you can still use the data in any of the 18 countries covered by Three's Feel At Home perk, including the US and Australia. While the SIM is primarily aimed at data-only devices like tablets and such, you can plug it into a phone and make calls from 3p from minute, or send texts from 2p per message.
If any of this sounds eerily familiar, it's because the new Data Reward tariff is almost identical to FreedomPop's UK offering. The mobile virtual network operator (MVNO), which coincidentally (or not) uses Three's network, has built its entire business on providing a free, barebones service, with overage charges and paid value-added features keeping it afloat. FreedomPop's Basic 200 plan includes 200 minutes, 200 texts and 200MB of data free each month, and the provider recently launched a new roaming SIM that focuses on free data you can use abroad.