Three UK has confirmed it has purchased UK Broadband Limited for £300 million.
The deal means UK Broadband Limited will become a wholly owned subsidiary of Three UK, while its 15,000 customers will move over to the new provider.
Dave Dyson, Chief Executive of Three UK, commented: "UK Broadband gives us an opportunity to expand our ambition to provide high quality and great value internet connectivity for UK consumers."
Kester Mann, principal analyst at CCS Insight, pointed out that much of the new spectrum being acquired by Three will not be compatible with most of today's mobile devices, which means it cannot be put to immediate use.
However, he said it is likely "to be a key band for 5G services, which will launch in the UK from 2020".
The government has already committed to spending £740 million on rolling out fibre broadband connections and 5G technology in its new industrial strategy.