Sure has completed its takeover of Airtel Vodafone.
The deal was approved by both Jersey and Guernsey's authorities.
Sure says it signals a £48 million investment in a 5G mobile network, and that islanders will benefit from faster speeds and greater coverage.
Sure Group CEO Alistair Beak called it an 'exciting day' for the future of Channel Islands telecommunications:
“We want existing and new customers to know that the large investment we’re making will lead to significant improvements to their connectivity, speeds and coverage, as well as value for money through innovative products and services.
"The new mobile network, complemented by our extensive fibre network, will mean we can stay ahead of future demand driven by our increasingly digital lifestyles.”
Airtel Vodafone staff have joined Sure.
As part of receiving permissions, Sure has committed to allowing Airtel Vodafone customers to continue on their existing plans for up to three years.
Initially, the two will continue two companies will continue to operate separately.
Sure has also made a deal with the CI Coop, which will launch Coop Mobile offering its own mobile services and pricing over Sure's network infrastructure to 'preserve competition and customer choice'.

Draft law scraps time limits on abortions in Jersey
Divide over approach to gender guidance in schools
Three charities awarded £500 grants in community campaign
Ministers back principle of social media 'restrictions' for under 16s
Passengers rerouted through Jersey Airport departures
A total ban on disposable vapes in Guernsey and Jersey is poised to take full effect
Islanders with COVID-19 symptoms reminded to avoid the hospital
2025 was the fourth warmest year on record