MP3 will beep when you send a text message or make a phone call. What is the reason?

This is when the mobile phone is talking, and there is a strong electromagnetic wave around it.

MP3 is an electronic product, which will be interfered by electromagnetic waves.

normal phenomenon

You remind me of my friend. Every time he likes to joke with me, he hangs up as soon as my phone rings.

It's depressing that I answer the phone every time. How does he know that I like listening to the radio? Every time I don't think about my mobile phone, the radio has a sound for a long time, which will be delayed by about 5 seconds.