Despite having the same dock connector as the fifth-generation iPod, the iPhone doesn’t work smoothly with all iPod accessories. In fact, when you plug an iPhone into an iPod speaker dock or similar audio accessory that uses the dock connector, you may get an onscreen warning telling you that the accessory isn’t designed to work with the iPhone.
Though you can click past this and still use the accessory, sometimes you’ll hear interference in the speakers. This is coming from the iPhone and has to do with the phone and data network reception.
Luckily, there’s a way to get around this — turn off the phone feature.
The iPhone offers something called “Airplane Mode.” This mode is designed to let you use the iPhone on a plane, where you’re not allowed to use a cell phone, but can use an iPod. Setting the iPhone to Airplane Mode will let it work smoothly with many iPod speaker accessories that use the dock connector.
Here’s how to turn Airplane Mode on:
From the home screen, tap Settings.
The first option you’ll see it Airplane Mode. Move the slider from off to on.
Now, when you dock the iPhone to a speaker, it should work fine. This won’t be the case with every accessory, but more often than not, it should work. Be advised, though, when Airplane Mode is on, you can’t make or receive calls.