If you bought yourself the most famous Apple iPhone phone, then you know that it comes with a headset with bad headphones, as is usually the case with Apple. But there is a button on the headphones, not everyone knows about all the functions of which.
So...
In the phone mode, when there is an incoming call, pressing the button leads to the answer to the call. During a conversation, pressing it will interrupt the conversation. And if you have the second line turned on and during the conversation, someone got through to you, then a long press will put the current interlocutor on Hold, he will hear your voice on the second. Switching takes place between the interlocutors with the same long press.
In the player mode (if you don't mind what you hear in these headphones), a single short press on the button stops or continues playback. If you want to switch to the next track of the playlist, then just double-click. And you can get to the previous one by performing a triple click.
It's just a pity that the quality of the headphones does not correspond to such a wide functionality of the button. Yes, and it will fail after 2-3 months of active use. Tested on three acquaintances on myself.