answered
2016-08-28 15:42:41 +0300
The reason is a different pin configuration. Nokia used the standard pinout: Left, Right, Mic, Gnd (from the tip to the sleeve). Jolla decided to monkey after Apple (just like they did with the micro-SIM size, even though a standard SIM would fit comfortably). Their pinout is Left, Righr, Gnd, Mic. Pressing the button shortens the Mic to the Ground and the music plays as it should. Otherwise the current needs to flow from the Left or Right pin through the speaker AND the microphone to the groumd, which is not ideal.
I do not know if it is fixable in software. It might be, depending on the hardware used, but I doubt it. Your best option is either get different headphones or an OMTP/CTIA adapter.
See also https://en.wikipedia.org/wiki/Phone_connector_(audio)#TRRS_standards.