T-Mobile US and Sprint laid out their arguments for a $26.5 billion merger as they made their first formal bid to win clearance for the deal from the Federal Communications Commission (FCC).

In a near 700-page filing to the regulator, the operators cited lower prices, greater competition and 5G leadership for the US as the key tenets of the deal.

The pair pointed to 5G as an enabler for a cascade of consumer benefits. In addition to securing US technology leadership, the companies said their ability to construct a massive 5G network would expand rural coverage, provide an alternative to fixed home broadband, create jobs and enable more choice in the video and enterprise markets.

Though critics worried the removal of a wireless competitor from the marketplace would drive consumer prices up, the pair argued the opposite is true, noting the depth of its 5G network and strong business incentives will keep costs down.

“If new T-Mobile were to do otherwise – for example, raise prices or reduce customer value under its rate plans – it would damage the Uncarrier brand, alienate its customer base, and leave the company with idle capacity.”

The message marked the start of what will be a lengthy review of the deal by regulators at the FCC and US Department of Justice.

But it likely won’t be an easy road. Regulators killed AT&T’s bid to buy T-Mobile in 2011 citing the need for four competitors in the market, and Sprint and T-Mobile abandoned their original merger talks in 2014 after the head of the FCC threatened to spike the deal.

Though current FCC chairman, Ajit Pai, placed less emphasis on the specific number of players in the market, T-Mobile and Sprint will still have their hands full proving fewer operators will translate to more competition and benefits for consumers.