"It is time for Apple to step up to the plate and put the safety of the American people first", the chairman added.
The FM chip has been an unknown part of smartphones for some time, and Pai has made a point in recent years to push phone makers to activate those chips, saying they can provide life-saving help during a crisis.
Pai could easily order Apple's compliance, but he has refrained from doing so because he understands that free market is involved. "The notion that Apple or anyone else would block this type of information is something that we find fairly troubling". LG, Samsung and Motorola have previously activated the FM chip.
But FM can be a vital source of news and information for users during emergencies, Pai said.
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Critics say it is a protectionist law, and multiple studies say it has cost the Puerto Rican economy billions of dollars. The company started offering aid after Hurricane Irma devastated a wide swath of the Caribbean earlier this month .
An Apple spokesman did not immediately comment on Thursday.
Pai wrote that he hopes Apple will "reconsider its position" in the wake of those hurricanes, which have devastated areas of the United States, including Texas, Florida and USA territory Puerto Rico. Chipmakers like Qualcomm and Intel have long baked FM radio tuners into the chips that enable Wi-Fi and cellular connectivity in iPhones and other handsets. Last month, Internet streaming through the app became available on Apple iOS, but the company didn't move to unlock FM chips in their phones. It's still far from ubiquitous-many higher-end phones still do not allow the functionality, and Verizon generally doesn't sell as many FM-enabled devices as its peers-but there's been some change. In Mexico, that number is 80 percent, Pai said. At the same time, he has refused to call for a mandate requiring the chip be activated in the phones and has expressed doubt that the FCC would be able to issue or enforce one.
"In recent years, I have repeatedly called on the wireless industry to activate the FM chips that are already installed in nearly all smartphones sold in the United States", the chairman said in a prepared statement. And that may be enough to encourage the high-profile company to reverse course and activate the chips that already exist in its phones.
Though it may not be obvious at first blush, most smartphones have the ability to stream local FM radio stations directly. "Because you just don't know what will happen".