I dont know how to set it as phone ring but here is one:
http://www.turkcell.com.tr/r/x/reklamfilmleri/gnctrkcllfilmmuzik.mp3

Other videos here:
http://www.video35.com/video_ara_turkcell

You can record MP3, WMA, or WAV files when you watch videos online with this program:
http://29984.rapidforum.com/topic=102571739004

KaDear