T-Mobile US president of technology Neville Ray (pictured, left) warned US operators relying on dynamic spectrum sharing (DSS) for their 5G rollouts in 2020 could be left in a bind, noting the technology had encountered a number of delays and challenges.

DSS is a highly sought after radio feature allowing operators to share a given block of spectrum between 4G and 5G. But on T-Mobile’s Q4 2019 earnings call, Ray highlighted vendor delays in delivering DSS capabilities and said one of the top radio vendors is “very late”.

He added testing uncovered issues with capacity loss, explaining “as you deploy DSS, it kind of eats away on the net capacity of the shared radio. Some of the early rollouts and workarounds and pieces that we’ve seen are pretty corrosive, and they will suck up capacity just by rolling out the feature”.

Unsurprisingly, the executive argued T-Mobile had plenty of room to continue deploying low-band 5G coverage with its 600MHz spectrum, while other operators like Verizon, which are expected to rely on the technology to push 5G into lower bands, could be facing a “big challenge” without it: “DSS is not going to materially help them.”

Net profit of $751 million in Q4 was up 17.3 per cent year-on-year, on revenue of $11.9 billion, up 3.8 per cent.

In its earnings statement, T-Mobile hailed a 6.3 per cent rise in service revenue, which it said delivered a record of $8.7 billion in the quarter.

Post-paid net additions topped 1.3 million, some 1 million of which were phone customers. However, T-Mobile is struggling to convert those new users into a solid revenue stream, with ARPU down 1.1 per cent to $45.79. Prepaid net adds of 77,000 were down from 135,000 in Q4 2018, with ARPU “essentially flat” at $38.54.

Full year profit of $3.5 billion was 20.1 per cent higher than 2018, with revenue up 3.9 per cent to $44.9 billion. Service revenue generated $33.9 billion of the total, a rise of 6.3 per cent.