Windows phones support Silverlight but the Silverlight player is limited as it can only play a stream with is both audio and video.
Audio only and video only are not supported in this player.
What's the codec of the stream being sent to Wowza?
You should be able to see if there is an issue in the Wowza logs.
If you recently changes the configuration files for example the Application.xml file to add smoothstreamingpacketizer to the LiveStreamPacketizers you will need to restart Wowza for the changes to take effect.