BT is to acquire mobile operator EE for £12.5bn. Plans for the acquisition were originally announced in December, after BT opted to go for EE rather than Telefonica’s O2.

The deal sees BT return to the mobile business and, at a stroke, become the UK’s largest mobile network, with 24.5m customers, 7.7m of whom are on 4G.

The transaction values EE at a multiple of 6x 2014 EBITDA (earnings before interest, tax, depreciation and amortization). EE’s previous owners, Deutsche Telekom and Orange, will hold a 12 per cent and 4 per cent stake respectively in the new business.

BT said it expects to generate revenue synergies by providing a full range of communications services to the combined customer base. This includes selling its broadband, fixed telephony and pay-TV services to those EE customers who do not currently take a service from BT.

BT also said it expects to accelerate the sale of converged fixed-mobile services to BT’s existing consumer and business customers, and to offer new services, using both companies’ product portfolios, skills and networks. By combining the BT and EE businesses, BT estimates that it should be able to generate an extra £1.6bn a year in sales.

The deal is expected to be finalised by March 2016, subject to approval from BT’s shareholders and regulatory authorities.

BT chief executive Gavin Patterson described the deal as: “a major milestone for BT.” He said: “It will allow us to accelerate our mobility plans and increase our investment in them. The UK’s leading 4G network will now dovetail with the UK’s biggest fibre network, helping to create the leading converged communications provider in the UK. Consumers and businesses will benefit from new products and services as well as from increased investment and innovation.”