What is the function of the alternate symbol on the currency key?

I recently switched back to my Priv and noticed a symbol on the physical keyboard that I've never paid attention to before. There's a speaker/audio symbol on the currency key. Using alt+currency key doesn't seem to trigger any action related to audio. What does this symbol do/indicate? It's also on the KEYtwo, KEYone, Classic, Q10, and Q5, but not Passport keyboards.

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It is for assistance

Posted via CB10

Turn speaker phone on and off. If your on a call and you press and hold the key it will go speaker phone.