Qualcomm and T-Mobile have successfully completed the first data call using Qualcomm's X55 modem, the first 5G chip for phones to support all 5G networks to be launched in the US in 2019, including T-Mobile's band 71 (600 MHz). All 5G phones currently on the market in the US use the X50 chip, which only supports mmWave bands and TDD bands such as Sprint's band 41. mmWave bands offer high speeds, but short range and poor building penetration. US carriers will only offer mmWave 5G in central areas of major cities. T-Mobile and AT&T will offer broader 5G coverage using sub-6-GHz FDD bands later this year, and the first phones in the US to support those networks will use this new X55 chip.