Back in January, Samsung announced that its phones in the US and Canada would have an active FM chip for listening to the radio. But the unlocked models didn’t have the software to support this functionality until the most recent update rolled out.
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One user does note that you need to make sure that you’re in the “basic / FM only mode” in the NextRadio app. If you aren’t, there’s a chance that you could be streaming music over your data feed instead of actually listening to the radio.
For the FM radio to work, though, you have to have a pair of wired headphones plugged into the Galaxy S9 or S9+ as it acts as the antenna. If you don’t still own the AKG buds that came with the headset, any pair of wired headphones will work.