Random beeps/tones while talking on iPhone (3Gs)?

Has anyone else noticed the iPhone 3Gs (my model) making random beeps or tones while talking? It appears to be when your wireless is enabled on the phone. As soon as wireless is disabled, these beeps during a phone call go away. This issue appeared during iOS 6.0.1 update.

The beeps occur at any time and are not part of a minute beep, notificiation beep, or any other type of iOS function. The phone was fully restored to factory and apps were added. The method to "get rid" of the beeps is to disable wifi and it appears to dissapear.

Anyone at Apple care to shed light on their Q/A process?