The present invention relates to a mobile set integrating a memory efficient data storage system for the real time recording of voice conversations, data transmission and the like. The data recorder has the capacity to selectively choose the most relevant time frames of a conversation for recording, while discarding time frames that only occupy additional space in memory without holding any conversational data. The invention executes a series of logic steps on each signal including a voice activity detector step, frame comparison step, and sequential recording step. A mobile set having a modified architecture for performing the methods of the present invention is also disclosed.