Interconnection of IP QoS capabilities between networks releases considerable value. In this paper we show where this value will be realised. We give technical and economic arguments for why QoS will be provided in core and backbone networks as a bulk QoS facility incapable of distinguishing or charging differentially between sessions. While between edge networks a vibrant mix of retail QoS solutions will be possible, including Internet-wide per flow guarantees. We outline cutting edge research on how to coordinate QoS between networks, using a session-based overlay between the edges that will extract most surplus value, underpinned by a bulk QoS layer coordinating the whole. We survey today’s interconnect tariffs and the current disconnected state of IP QoS. Then we describe a commercial ‘model of models’ that allows incremental evolution towards an interconnected future. The paper covers intertwined engineering and economic/commercial issues in some depth, but considerable effort has been made to allow both communities to understand the whole paper.