Optus is now delivering carrier aggregation on three separate mobile networks to Melbourne customers with two of Samsung's new-model smartphones.
The telco started piloting the 3x CA technology last month, using one FDD (frequency division duplexing) and two TDD (time division duplexing) networks in the Newcastle area.
It said it achieved mobile data download speeds of 317Mbps. Optus is currently the only local telco using TDD technology.
Following the Melbourne go-live, Optus plans to switch on the 3x CA technology in the Sydney central business district early next year, followed later by Brisbane and Adelaide CBDs.
The technology will work with category 9 devices such as Samsung's Galaxy S6 Edge+ and Galaxy Note 5 devices, which become available this Friday.
2x CA is already available on the Optus 4G Plus network in selected areas of Sydney, Melbourne, Brisbane, Adelaide, Canberra, Hobart and Darwin, as well as 20 major regional centres.