The cash-back part of the discount is not available straightaway – it has to be claimed from the retailer about six months after taking out the contract. This means for the first six months you may be paying a higher rate but in the long run the cost will be significantly cheaper. The value of the cash-back can be hundreds of pounds but you have to remember to fill out the forms.

If you stay within your free minutes and texts, have chosen a free handset and claim all your cash-back you could actually pay nothing over the contracts lifetime.

Users have complained about poor customer service, lack of contactable premises and expensive premium rate customer service numbers, so be wary when changing from a tangible phone provider to an online company. Be aware that you may have to fight for your cash-back, so be prepared to be persistent.

When taking out a cash-back deal you should buy from one of the bigger companies, such as e2save.com or mobiles2yourdoor.co.uk (which are owned by the Carphone Warehouse and Phones4u respectively), which are extremely unlikely to go bankrupt. If you buy from a smaller company and they go bankrupt, you won’t get back any of your money. The bigger companies are also less likely to refuse to give you your money back.