How to use a desk lamp, but do not pay for electricity

Over there and over there, I read that the uxsight.com online store offers a desk lamp with eight LEDs, which should not be plugged into a regular outlet, but into a telephone (RJ11 standard). For the buyer, this means free coverage, because the telephone operator pays for electricity.

The stated lamp life is 100,000 hours, and the price is less than 5 bucks.

Looks like this:
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