Conscience as a call is intriguing, a call that can bring us back from where we have gotten lost in the 'they'. A quote that I found useful in my understanding, "...Dasein, as a Being-with which understands, can listen to Others. Losing itself in the publicness and the idle talk of the "they", it fails to hear its own Self in listening to the they-self" (315). It is when Dasein has lost itself in others and idle talk that it must find itself and call itself back to itself.
"The tendency of the call is not such as to put up for 'trial' the Self to which the appeal is made; but it calls Dasein forth (and 'forward') into its ownmost possibilities, as a summons to its ownmost potentiality-for-Being-its-Self" (318). The conscience then, might be understood to bring the Dasein forward and out of the "they" it was previously lost in and become 'itself' or its own thing instead of what "they" made it out of distraction.
I began to get confused starting on page 320 around the number along the side, 276-hopefully what followed is something I can better understand tomorrow.