Mobile carriers have been fighting for years over which has the fastest wireless network. Some studies say it’s Verizon while others have singled out T-Mobile. All the while, the carriers have been adding technology to make everyone’s experience better. Well, everyone with a fairly new smartphone.
Now PC Magazine has uncovered some truly insane download speeds available in the real world, on a street corner in New York City. A tester for network testing firm Ookla achieved download speeds as high as 531 megabits per second (or about five to 10 times faster than what typical users experience) using a phone on T-Mobile’s network at the corner of 45th St. and Third Avenue in Manhattan. In 13 tests, speeds averaged 503 mbps, fast enough to download a high-definition digital copy of the Oscar winning movie The Shape of Water in 2 minutes.
The super-fast downloads did not require equipment from the next generation of wireless networking, known as 5G, which T-Mobile and other carriers are slowly installing around the country. And they don’t require that customers pay extra or download special apps on their phones. Instead, the speed relied on a current feature of 4G LTE networks that is also being slowly added, called Licensed Assisted Access, or LAA for short. T-Mobile says it is adding LAA capability around the country, focusing on denser urban areas.
Get Data Sheet, Fortune’s technology newsletter.
At the New York City street corner, recent smartphones can connect to T-Mobile’s network using not just the usual cellular spectrum bands of 1700 MHz and 2100 Mhz, but also can use LAA to piggyback on airwaves in the 5GHz band that are usually used by Wi-Fi gear, PC Magazine reports. This unlicensed spectrum is available even in places where Wi-Fi gear is plentiful, like New York City.
But while carriers including Sprint (S) and AT&T att(T) are widely deploying several other needed technologies to reach the super-fast speeds, LAA-compatible gear was just approved for use by the Federal Communications Commission last year. The other key technologies are carrier aggregation, which lets a phone receive downloads on different spectrum channels at the same time, 4X4 MIMO, which multiples the number of antennas in a phone, and 256QAM, which uses higher power output to cram more data in a wireless signal.
In addition to the slow rollout of LAA, another limiting factor is that not every phone is compatible with the feature. Apple’s (AAPL) iPhone X and iPhone 8, for example, do not. But versions of the Samsung Galaxy S8, Note 8, and Galaxy S9, along with the LG V30 and the Huawei Mate 10 Pro that work on T-Mobile’s (TMUS) network can access the extra airwaves.
