Samsung's latest flagship handset phone can hit incredibly high peak speeds, and it may get even faster over time.

Back at its Galaxy S10 Unpacked launch, Samsung unveiled its first 5G handset, the Samsung Galaxy S10 5G.

Samsung also announced that the S10 5G would be a Telstra exclusive at launch, with a special deal for S10+ owners who signed up early enough to score the phone as a free upgrade once it was available.

The Galaxy S10 5G will go on sale through Telstra on 28 May, which happens to be tomorrow. At a press launch this morning, I had the chance to see the S10 5G get put through its paces with the Speedtest app to see just how fast Telstra's 5G network can be pushed.

The Samsung Galaxy S10 5G doesn't disappoint, with a peak observed speed using the app of 1,254Mbps downstream. It's not quite as nippy for uploads, with 64Mbps upload speeds observed.

There are a few obvious caveats in play there. Telstra's announced 5G coverage zones aren't extensive as yet, with just 10 cities across Australia having any 5G coverage. Telstra says it'll expand that to 35 cities within the next 12 months, but right now, there's just not that much coverage. At this stage, a day before launch, it's also not as though there are that many competing devices slurping up Telstra's available 5G bandwidth.

Still, that's plenty fast, so it should be very good for streaming purposes or ultra-fast downloads. Although at those speeds, you will burn through a regular plan's data inclusions even faster, so a plan with unlimited data might be a good match.

For what it's worth, Telstra reckons this is only the beginning, claiming that its 5G speeds should hit "around double what we see on 4G" under current network software. The final specifications for 5G were only ratified back in September 2018, so what Telstra's running on is very early software indeed.

The Samsung Galaxy S10 5G is a Telstra-exclusive handset that will be available to customers from 28 May 2019. There's no word as yet as to when (or if) it'll also be sold in Australia on an outright basis.