The network was built between November 2005 and September 2006, and launched in October 2006. As of 2007[update], Next G was the largest mobile network in Australia, providing greater coverage than other 3G providers in Australia and over three times greater than any 2G provider in Australia. In December 2008, the Next G Network was also the fastest mobile network in the World, delivering theoretical network speeds of up to 21Mbit/s[dated info] utilising features of HSPA+ and Dual-Carrier HSPA. In February 2010, Telstra increased the speed up to 42Mbit/s making the Next G Network once again the fastest mobile network in the world.
On September 26, 2011, Telstra launched its 4G 1800 MHz LTE network, claiming typical download speeds of up to 40Mbit/s.
It was built to replace Telstra's CDMA network which operated from 1999 until 28 April 2008. Telstra opted to use the 850 MHz band for Next G in preference to the more common 2100 MHz band, since it requires fewer base stations to provide coverage, providing a lower capital cost. This network was implemented under contract by Ericsson as part of a project internally dubbed "Jersey" and launched on 6 October 2006.HSPA technology was included in the network to provide Australia's first wide area wireless broadband network. The efficiency of the Next G network and its coverage has been challenged and scrutinised since its launch, requiring Telstra to go back to areas with average coverage, particularly rural towns to improve its coverage footprint. On 18 January 2008, Stephen Conroy, Minister for Communications, declined the proposal for Telstra to switch off its CDMA network on 28 January 2008, stating that whilst the Next G network provided coverage equal to or better than the CDMA network, the range of handsets available was not yet satisfactory. On 15 April 2008, the Minister gave approval to close the CDMA network after 28 April 2008. Telstra closed the network nationally during the early morning hours of 29 April 2008.
While most wireless modems offered by Telstra allow peak download speeds of up to 7.2 Mbit/s, a modem by Sierra Wireless was announced in 2009 that supported increased throughput. The "USB 306" is marketed and sold by Telstra as the "Telstra Turbo 21 Modem", and was available in limited quantity in early 2009. By April, the "Turbo 21" was available to customers and offered peak download speeds of 21 Mbit/s, although actual speeds vary between 550kbit/s and 8Mbit/s. As of June 2009[update], Next G network HSUPA upgrades in selected regional and metropolitan areas, combined with software updates for the "Turbo 21" modem, will allow peak uplink speeds of up to 5.76 Mbit/s.[dated info]