The deal will see current market leader Telefonica’s O2 pushed into second place, followed by Vodafone in third place. The two companies are also thought to have been in talks with Deutsche Telekom to acquire T-Mobile.
The joint venture will have a combined mobile customer base of 28.4 million, making up approximately 37% of UK mobile subscribers. The companies say the new venture is expected to generate savings of over €4bn (£3.5bn).
The T-Mobile UK and Orange UK brands will be maintained separately for 18 months following completion of the transaction. During that period branding alternatives for the new joint venture will be reviewed.
Earlier this year it was reported that Deutsche Telekom had been under pressure from key shareholders to either sell or merge its UK business with a rival company.
Last week, T-Mobile launched the latest phase of its “Life’s for Sharing” ad campaign featuring vox pops centred on the way people use the mobile operator’s products to make the most of their money.
The first two creatives, “Dance” (pictured) and “Sing-along”, involved flash mob activity.
Orange UK currently uses Fallon as its ad agency, while T-Mobile works with Saatchi & Saatchi.