1. Headset Button does not work as play/pause on single press and next track on double press just like on stock
Credits to: @imanesaurus
key 226 HEADSETHOOK
key 256 BUTTON_1
key 226 BUTTON_1
key 256 HEADSETHOOK
Install this one and apply the fix. You can now uninstall the app
Contact Sync Fix
Credits to: @chongns
a. to edit "snd_soc_msm_Sitar" in folder /system/etc/snd_soc_msm
b. find comment "Handset Rx device for voice call"
c. increase the value of 'RX1 Digital Volume':1:68 recommend in between 75 to 80, i use 78
(thanks to a member who post this, sorry forgot who's the name is.0)
d.make sure the permission is rw-r--r--, than reboot.
Credits to @Marius Cristian