The new iPhone, smaller than the current model and offering faster surfing speeds and a GPS connection, goes on sale in the US today and will be available to UK customers next month.
In the UK, where O2 has an exclusive contract with Apple, customers who sign up to the most expensive 18-month contract, costing £75 a month, will be offered the iPhone handset for no extra charge.
It will also be available to pay-as-you-go customers for the first time.
The change in strategy is designed to help Apple sell 10m iPhone handsets around the world this year, following disappointing sales in Europe. Previously, Apple charged customers a one-off fee for its iPhone handset in addition to a committment to sign a contract with the relevant network partner.
Apple has sold 5.4m iPhones, a small proportion of the £1.2bn global mobile phone market that is dominated by manufacturers such as Nokia, which sold 437m phones last year.
The iPhone has been popular in the US but of the 5.4m handsets sold, Jupiter Research estimates that fewer than 350,000 were shifted in Europe.
Apple's original strategy gave the company an estimated 15% of the operator's average revenue but under the new model, with operators paying to cover a proportion of the cost of the phone, Apple will take a smaller share of that revenue.