I believe I have found a bug in the audio output calls. I did not notice the problem before; I was previously using my SGH-T599N device without any calling privileges.
After starting at least an outgoing call (I am not certain about incoming calls), the true volume output of the device is lower than what it should be, even though the device may be set to a high volume. The volume may be increased by using the setting/buttons to lowering the volume setting. Although the volume setting appears to be lower the true volume output may actually increase. Afterwards, the volume setting may be increased and there may be an increase in the true output volume. This problem is rather annoying.
Prior to making a call, I have the volume set to maximum (the level at which I tend to leave the volume at).