To answer the question, ALL CELL PHONES HAVE BUILT IN FM RADIO
Every last cell phone in production can receive FM radio. Every last Iphone, Android phone, and dumb brick phone can, even if it is sold in America and you do not realize it can receive FM. Directly identical phones in Mexico, ALL have FM radio, 100 percent of them, no matter how cheap or expensive the phone is, or what platform it is on.
There is some discussion about this going around on the web, where people are wondering. Well, wonder no more, you can't sell a phone to a Mexican if that phone can't receive radio, and that is true in all of Latin America, Africa, and most of Asia. These markets dwarf the American market, and since the parts that do it are so cheap, manufacturers do not make different phones for different countries, all they do is enable the feature or disable it with the software.
Even if the phone is totally deactivated, the FM radio will still work. Additionally ALL phones in Mexico have MP3 players built in (if they are not too cheap to have an SD card) and the MP3 player will always work, regardless of whether or not your phone is in use as a phone.
Totally possible in Mexico: A smartphone with no service, that uses wifi, plays MP3's, works as a camera, has an FM radio and is totally useful, except to make calls over the cell system. Kids run around with old smartphones all the time, they can't make calls but they play games and surf the web constantly. Mexicans would not have it any other way. Why do Americans settle for crap?
Well, because a few Technocrats want you to use your data plan to stream audio, rather than just turn on the FM radio, and will brick your phone as soon as service stops BECAUSE THEY WANT MONEY AND YOU DON'T KNOW WHAT OTHER PEOPLE HAVE. That's why.