Go to Settings > Cellular > Cellular Data Options. If you see this screen, your device has 5G activated . If you don’t see this screen, contact your carrier to confirm that your plan supports 5G.
Read moreWhich Samsung phones are 5G?
The Samsung S20 5G, S20+ 5G and S20 Ultra 5G all work on T‑Mobile’s nationwide 5G network. The S20+ 5G and S20 Ultra 5G are also able to tap into millimeter wave (mmWave) 5G, so customers with these devices can get a speed boost in hotspot like coverage areas where mmWave is deployed.
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