I don’t have an android 4.3 device. Mine’s Gingerbread. But you might! Previously, we have found that many people with android 4.3 could not get the magicJack app “Talk Free” to work properly. Check out this post and its comments for more information. Help us out! If the app update fixes the incompatibility for you, please post in the comments.
Update: Frodo1B confirms that it works for Nexus 7 on his Android 4.3… Any other confirmations?
Update 2013.09.10: Others can confirm that Android 4.3 does NOT work on their devices.