Telstra has announced it will switch off its 3G network in June 2024 repurposing the spectrum used to carry data and voice calls over its oldest mobile network technology to help grow 5G.

"Today, as part of our program to continually upgrade our network to the latest technology and expand our 4G and 5G coverage, we’re announcing the eventual switch-off of our 3G technology," Telstra group executive networks and IT Nikos Katinakis wrote in a blog post.

"This will not happen until June 2024 – more than four years away."

The telco has invested $8 billion on its mobile network in the past five years to 30 June 2019. This includes investment in its 5G network launched in May, which is currently available in selected sites in 10 cities, with plans to expand to 35 cities over the next year.

"Similarly to when we turned off our CDMA technology and re-purposed its 850MHz spectrum for 3G services, switching off 3G will let us again repurpose this same spectrum this time to 5G to allow us to continue growing and improving our latest generation 5G technology to meet your data needs in the future," Katinakis explained.

"We are giving our customers more than four years’ notice to prepare for the change ahead of the June 2024 closure date."

Telstra pledged continue to upgrade and expand its 4G coverage to a "materially equivalent size and reach to our 3G footprint".

"Most customers will generally notice an improvement in speed when using a compatible device – in many cases a substantial one. We are working to assess our product range and all current areas with 3G only coverage in order to give you the best possible experience on 4G and 5G," Katinakis added.

In December 2016, Telstra switched off its 2G network. At its investor day in November that year, Brendon Riley who was the acting COO at the time said that the retirement of the 3G network could be expected after 2020. Riley is the group executive at Telstra Enterprise.

In 2018, Telstra began declaring mobile sites ‘5G-ready’, gearing up tolaunch services based on the new standard this year. More than 200 of the company’s mobile sites are now ready to deliver 5G services.