For anyone with a massive data requirement in the UK, the O2 Unlimited data SIM is a great solution. The real monthly data usage limit is 650GB per month, but that is quite chunk of data. It is ideal for streaming live video such as remote security cameras or replacing fixed line broadband.

The O2 unlimited data SIM is perfect for using in conjunction with M2M applications, routers and M2M SIMs. It can be used as a primary SIM in a dual SIM Robustel router with a Multinet 3 M2M SIM covering the other 3 UK networks as a back up solution. A Robustel router can be configured to automatically switch to a back up SIM if the O2 signal becomes disrupted. The O2 Unlimited SIM is the cheapest SIM for bulk cellular data in the UK.
O2 Unlimited Data SIM for a 12 month contract is priced at £30 +vat per month or £28 for a 2 year contract. The O2 Unlimited SIM is ideal for anyone who knows they need a lot of data, but do not know for sure. As a guide for streaming video HD 720p uses about 0.9 gb per hour, so the unlimited O2 MBB can just about cover that level of 24/7 video streaming. In the case of 1080 HD it might be worthwhile running 2 unlimited cards in a dual SIM slot Robustel router as the data requirement for HD 1080 is approximately 1.1 TB per month.