For anyone worried about getting a long-term subscription, Smarty was the SIM card provider, combining their one-month work plans with some of the best value packages around. But now iD Mobile is catching up. Like Smarty, iD Mobile offers flexibility in the form of rolling one-month contracts so you can leave at any time. However, iD has always focused on low-cost and low-cost data plans, but now it has competed in the big data market. With unlimited data, talk and text for €20 a month, iD has matched one of Smarty's best deals. But the thing now is that these two offerings are almost indistinguishable. Both offer the same data, calls and SMS at the same price, both allow connection sharing, both overlap on the Three network and offer the same roaming options. What we're really saying is that you have two identical options for one of the best SIM-only deals on the market. Of course there are other unlimited plans, GiffGaff offers a one month unlimited mobile plan but at an inflated cost and with imposed speed limits and Vodafone, EE and O2 will charge you a blindly high price. That leaves Three as the only other option to consider as the cheapest plan in the UK. Find out more below.