T-Mobile shows why it's still too early to buy a 5G phone

Key Points
  • T-Mobile's nationwide 5G network will launch on Friday, Dec. 6.
  • But don't buy the new 5G phones yet. They only support 600MHz 5G, which is slower than other limited 5G networks from carriers such as Verizon and AT&T.
  • Eventually, you'll have phones that support low-band, mid-range and wide-band 5G. Those are the phones you'll want to buy. But they're not going to be available until 2020.
John Legere
Mark Neuling | CNBC

T-Mobile's nationwide 5G network launches on Friday, the company announced Monday morning.

But don't fall for the marketing hype. It's still too early to buy a 5G phone, even though T-Mobile is now taking orders for two new ones, including the Samsung Galaxy Note 10+ and OnePlus 7T Pro McLaren.

It's still a big step, though.

T-Mobile will turn on its 600 Mhz 5G network, which will cover most of the country. That's impressive, since most of the 5G networks you've heard about so far are only available in limited areas in a small number of cities. The trade-off though, is T-Mobile's network is using low-band 5G, which means it's good at providing slightly boosted speeds inside buildings and is available in far more places than what competitors offer.

Some of the 5G Ultra Wideband networks you've heard about from AT&T and Verizon provide the opposite. They have super fast speeds, but only work in really small pockets when you're standing near a tower outside. PCMag says you can expect a boost of about 50 Mbps with T-Mobile's new nationwide 5G network. So, you might see 150Mbps if you have a new 5G phone instead of the 100 Mbps download speed you have on 4G LTE.

To put that in perspective, if you're downloading a 3 GB movie, you might be able to download it in about 30 seconds or so if you have a really good 4G LTE connection. If you get that 50 Mbps boost, you'd download the same movie in 20 seconds. The bump in speed isn't a good enough reason to buy a new 5G phone right now.

Verizon and AT&T's 5G networks are roughly 10 times faster than LTE, with speeds hitting around 1,000 Mbps (or 1 Gbps) or more. That means you can download a 3 GB movie in just a few seconds.

T-Mobile has some of these networks active, but only in six cities. And the two new phones you can buy today don't support those areas. Only one phone does, the Samsung Galaxy S10+ 5G, but that doesn't support the new 600MHz network. Plus there are overheating issues you need to worry about with some of those faster networks.

Here's why you should wait before buying a 5G phone today: Eventually, carriers are going to sell phones that support all the various 5G technologies that are starting to light up across the country. That means you'll have one device that can access the top-tier speeds offered by Verizon, AT&T and T-Mobile, or the slower, but still fast enough, speeds that T-Mobile announced Monday.

You can see why T-Mobile wants to merge with Sprint. If the merger goes through, the combined carrier will have all three major 5G technologies available.

Unfortunately, there aren't any phones that support all of those networks yet, so anything you buy now would be out of date as soon as there are. It's best to wait until later in 2020 to start looking at 5G phones.

What is 5G?
What is 5G?