Samsung’s new lineup of Galaxy S10 phones is arriving just as higher-speed 5G networks are in the process of launching worldwide — timing that will force some early adopters to decide between buying a late-stage 4G phone in March or a first-generation 5G phone in June. But one carrier isn’t making its customers choose: Buying the Galaxy S10+ will entitle them to upgrade to the Galaxy S10 5G “at no extra cost” when it’s released.

If the deal sounds too good to be true, that’s because it’s an exclusive promotion between Samsung and Australian carrier Telstra, which has been aggressively trialing 5G in the country ahead of a larger 2019 rollout. Telstra is promising to be the country’s first carrier with the Galaxy S10 5G, which is expected to come first to Verizon around June, before hitting other carriers.

“This delivers the best of both mobile worlds for our customers,” said Telstra consumer executive Kevin Teoh. “Getting their hands on a smartphone by one of the world’s biggest brands, powered by our world leading 4GX technology, and then being able to upgrade to the next generation in mobile technology later in the year is an exciting opportunity that we are looking forward to sharing with them.”

As of now, the Galaxy S10 5G’s data performance remains a question mark on any 5G network, including Telstra’s. Samsung has said only that the phone is capable of 2Gbps download and 150Mbps upload speeds over LTE, while supporting both millimeter wave and sub-6GHz frequencies for 5G connectivity. Some, if not all, versions of the S10 5G are expected to use Qualcomm’s Snapdragon X50 modem, which promises peak download speeds in the 5Gbps range.

But Telstra is only promising “ultrafast speeds and lower latency” for the S10 5G at this point. The company also says that it has 200 5G sites across Australia, including parts of 2-kilometer radiuses in the city centers of Adelaide, Brisbane, Canberra, Melbourne, Sydney, and Perth; more substantial coverage in the Gold Coast metro area; and some regional coverage in Hobart, Launceston, and Toowoomba.

Users upgrading to the S10 5G will, however, benefit from other improvements. The newer model will include a larger 6.7-inch screen, front and back 3D depth-sensing cameras, and a 4,500mAh battery with support for 25-watt fast recharging. It will also be a few millimeters larger than the S10+ it replaces, and customers will need to return their S10+ phones “in good working order” within 21 days of receiving their S10 5G devices.

One other hitch: In order to qualify for the 5G upgrade, Telstra customers will have to lease or buy the Galaxy S10+ with a two-year service contract, making a collective commitment of at least $1,800 (U.S.) for both the phone and 3GB of data service — an advertised lease with a more 5G-ready 160GB of data will cost $2,200. Purchased alone, the 128GB base model of the S10+ has a U.S. retail price of $1,000. Prices have not been announced for the S10 5G.