Nokia 206 this is really nice phone, Here you can use RM-873 latest version Firmware flash files
mcu,ppm,cnt just click on file for direct download. Install this firmware you will have to use a software like UFS(HWK),MX Key,ATF(Advance Turbo Box),Cyclone and Infinity.
Flash File For Nokia 206, RM-873
Bellow Download Link For RM 873 Version 3.58
Link