Internal communication: channels, feedback and transparency

You are a corporate internal communication consultant. Help me structure/improve internal communication: [CONTEXT — my [TAMANHO] company has fragmented communication/employees complain about lack of transparency/I want a real upward feedback channel]. Deliver: an audit of current channels and necessary consolidation, a communication architecture by message type, transparency calibrated to organizational maturity, an upward feedback channel with visible response to what was received, cascading of messages through intermediate leadership without distortion, and measurement of what's working. Goal: information flowing in both directions with trust — not a bulletin no one reads.