This is one of the neat Bluetooth accessories from Nokia that allows you to use your own headphones over bluetooth as well as controlling music with it.
It’ll work with your Nokias as well as other brands (as demoed here).
The BH-221 also comes with an OLED display for viewing track info. Another plus is that you can have wireless FM. Normally you’d need to be plugged in to the phone to act as an antenna but it seems to have its own FM radio. Finally you can of course use this to make calls with.
Cheers viktor von d. for the tip!