I use an O2 simplicity contract monthly renewable with "unlimited" internet for £20/month, I preferred to pay the N900 full price (well after cashback and discount around £370) that always works out cheaper than locking myself up on long term contracts. Forgot to mention that I find the coverage and speed really good
Data Bolt On, Smartphone Bolt On and Blackberry Bolt On Terms for mobile web usage 1. The Web Bolt On, Smartphone Bolt On and BlackBerry Bolt On allows you unlimited use of Telefónica O2 UK Limited‘s Edge/GPRS/ 3G networks (as applicable to your handset), for personal internet use via your mobile phone. All usage must be for your private, personal and non-commercial purposes. You may not use your SIM Card: * in, or connected to, any other device including modems; * to allow the continuous streaming of any audio / video content, enable Voice over Internet (Voip), P2P or file sharing; or * in such a way that adversely impacts the service to other O2 customers. If O2 reasonably suspects you are not acting in accordance with this policy O2 reserves the right to impose further charges, impose network protection controls which may reduce your speed of transmission, remove the Web Bolt On from your account or disconnect your tariff at any time, having attempted to contact you first.