access this link
it's in chinese but you can use google to translate it, anyway the
images are saying everything.

i've seen a lot of topics opened about this problem, most of them
closed now so here it is guys. anyone can do it so you don't need to
pay 50$ for a cable.

good luck!

ps: you can try also to search "3300 f-bus" on google image search for
some more hints!

See More: Nokia 3300 F-BUS cable to 2.5mm connector or Serial cable