Since this update, my ringtone for incoming call plays out the receiver speaker instead of the rear speaker. Going into Skype settings and clicking Test Audio, plays the ringtone out the earpiece. I've reset Skype, uninstalled with a reboot before reload and even wiped my phone. Also, turning on phones vibrate only adds a chirping to the ringtone and no vibrations. This all used to work. I have no SD card installed.
As a workaround I stay plugged into headphones or speakers at all times to hear incoming call ring. The sound for message notifications is fine as are all other sounds. This happens to my wife's 640 also. We're running Windows Phone 10 1703.