We all own a smartphone, but some of us choose to sign up to a lengthy contract with a network provider, while others may choose to buy their phone outright and add a SIM-only plan. With regular mobile retailers, you're usually required to pay a large upfront payment and then be faced with high monthly bills for a tariff that's not always good enough. Buying SIM-free is the better option, but until recently you faced a hefty lump sum to pay upfront for the phone, with most of the flagships now costing well over £500 - that's not the kind of money everyone has readily available.

UNSHACKLED.com is a new retailer that wants to rip up the rule book by combining the two methods to give you the best possible choice of phones and the widest choice of SIM-tariffs out there, so that you can control the costs of your monthly payments and keep the freedom to change whenever you want.

With UNSHACKLED.com, all of the phones are completely unlocked and SIM-free. You choose any phone you want, including all the major flagships: Apple iPhone 7 and iPhone 7 Plus, Samsung Galaxy S7 Edge and the Google Pixel. You can either buy these outright or you can choose how much of an upfront payment you'd like to make.The upfront payment can be as little as £19 or more if you have an old phone you want to trade-in.

The rest of the amount you pay for the phone is spread out over 24 months to mimic the set up of traditional phone contracts and give customers the kind of payment structure they're familiar with. However, what's completely novel is the ability to finish paying off the phone whenever you like, so if you wanted to pay a big chunk off at any time, or sell the phone on so you could upgrade to a new handset, there's no penalties for doing so. This is a massive shift away from the early termination fees found in traditional phone contracts and allows you full control over when you change phones.

Once you've chosen your phone, you can then pick whichever SIM you like. All 16 of the UK mobile network providers are covered, including big names such as EE and Three as well as other perhaps less well-known ones such as The Peoples Operator and LIFE Mobile. As a fully independent retailer, they don't need to push you towards a particular 'top deal' of the week to hit commission targets, they're just there to help you choose the plan that works best for you.

You can choose whether you want a 1 month rolling SIM contract or a 12 month fixed contract. With the 1 month, you're able to change your tariff every monthshould you find you're not using all your minutes, or you need more data, for example. There's handy guides on the site for calculating how much data you actually need to buy, so you don't end up paying for more data than you need, or being charged for going over your data allowances, two of the main reasons monthly phone bills cost more than they should.

There's also a free service available called MobileWatch, where you can sign up to get alerts if a better deal comes along for you. They compare the deal you're on to what's new on the market, let you know when there's something cheaper available and help you switch over to the new plan without any hassle.

Unlike their competitors, UNSHACKLED.com isn't tied down to any particular networks, it's literally unshackled from them. This means you have the freedom to choose a phone and tariff that's perfectly suited for you and what you need, not just suited to what a network provider wants to sell you. And before you think this is just another start-up, the team behind UNSHACKLED.com has a combined 96 years of experience working in the mobile industry, putting all that expertise into building a better, more customer-focused way to buy your mobile.