Vodafone has finalized its merger with CK Hutchison’s Three in the UK.

The long-awaited £15 billion ($20.3bn) deal was confirmed this morning (June 2). The new company will be called VodafoneThree.

First announced two-and-a-half years ago, the deal will create the UK’s biggest mobile network operator, with an estimated 29 million customers. It also consolidates the number of network operators from four to three.

“The merger will create a new force in UK mobile, transform the country’s digital infrastructure, and propel the UK to the forefront of European connectivity,” said Margherita Della Valle, Vodafone Group Chief Executive.

“We are now eager to kick off our network build and rapidly bring customers greater coverage and superior network quality. The transaction completes the reshaping of Vodafone in Europe, and following this period of transition, we are now well-positioned for growth ahead.”

As part of the merger, Vodafone will own 51 percent of the company, while Three will own the remaining 49 percent stake. After three years following completion and subject to certain conditions, Vodafone may acquire Hutchison’s stake via a Put and Call option.

Vodafone noted that it will fully consolidate VodafoneThree in its financial results, with the company set to be led by Max Taylor, currently Vodafone UK CEO. Meanwhile, Three UK’s CFO Darren Purkis will continue in the role at the merged entity.

During the next decade, VodafoneThree will invest £11bn ($14.9bn) on its 5G mobile network, with £1.3bn ($1.8bn) to be invested in capex alone during the first year.

“As we have demonstrated in other European markets, scale enables the significant investment needed to deliver the world-beating mobile networks our customers expect, and the Vodafone and Three merger provides that scale,” added Canning Fok, deputy chairman of CK Hutchison and executive chairman of CKHGT. “In addition, this transaction unlocks significant shareholder value, returning approximately £1.3 billion in net cash to the Group.”

Both companies said the merger will help to deliver cost and capex savings of £700 million ($948m) per annum by the fifth year after completion.

Gaining approval for the deal hasn’t been straightforward for the two companies.

Aside from the concerns put forward previously by the Competition and Markets Authority (CMA), rival telco BT hit out at the deal, noting it would “create a merged entity with a disproportionate share of capacity and spectrum.”

The deal itself only got approval in December from the CMA following an 18-month investigation into the proposed merger.

The deal also received a lot of backlash from the union, Unite, which campaigned against the merger. Unite said the deal could pose a threat to the UK’s national security, noting Three’s parent company CK Group’s ties to Beijing.

Vodafone continues to consolidate

For Vodafone, the deal represents further consolidation for the carrier in Europe.

Since Della Valle took over at the telco two years ago, she’s overseen sales in Spain and Italy as part of the telco’s strategy to consolidate its business.

“The merging parties have little time to celebrate. Now, the hard work really begins as they set about implementing the many connectivity improvements they’ve long promised,” said Kester Mann, director, consumer and connectivity at CCS Insight.

“For many UK mobile users that have struggled for too long with poor signal, the upgrades can’t come soon enough.”

Mann added that the high-profile merger deal could be seen as a major positive for the European telecom sector.

CEOs at some of Europe’s biggest mobile carriers have ramped up calls for more consolidation within the market, including cross-border M&A.