Telstra has the fastest mobile data network in Australia but the once-ridiculed Vodafone now matches the dominant telco for high-speed 4G coverage.

That's according to a new report by wireless mapping company OpenSignal, which compared the performance of Australia's three largest telcos based on 15 million data samples crowdsourced from 7904 users.

The results show Telstra leading the pack for 4G speeds, with average downloads of 23.6 megabits per second, as well as overall speeds, averaging 17.1 Mbps across both 3G and 4G networks.

Optus and Vodafone were tied on 4G speeds, both averaging about 19 Mbps during the test period from February 1 to April 30 this year.