HamSphere 4.0 uses audio codecs by default. Codecs compress the audio to require lesser bandwidth. If you are using digital modes it is virtually impossible to transmit via VOIP systems using encoded audio.
By using this Codec Selector you can disengage the audio codecs and transmit undistorted/uncompressed audio over HamSphere. Please note that the bitstream in Codec OFF mode is about 150kbps compared to about 50kbps with codec.