Apple is to open the iPhone 3G to Orange and T-Mobile at the end of its two-year exclusive deal with O2.
The move will challenge O2's prices and tariffs, but the company will retain exclusivity for the iPhone 3GS, according to Mobile Today.
The move will enable Apple to increase sales of the older model phones, while continuing sales of the new iPhone 3GS with O2.
Orange and T-Mobile both carry the iPhone in several other countries and could start doing so in the UK as soon as September.
Many UK consumers have been put off the iPhone by the pricing from O2, leading many to import iPhones and "jailbreak" them for use with other operators.
In February, T-Mobile announced it had added network acceleration technology from F5 and Bytemobile to support the rise in the use of mobile data due to the iPhone and the popularity of USB 3G dongles.