 Let us continue with the transport stratum functions and we are going to look at the transport functions as we were discussing in the last module. Here the transport functions can be seen to be encompassing the core network side, the gateways which are the edge routers and the media handling capability provided by the transport functions. First the core functions. These are the functions which provide the data or the traffic actually to the core. So the traffic that is coming from the access is presented to the core. Since the traffic at the access side is being managed under quality of service, likewise it is also desired that the quality of service is sustained once the traffic enters into the core network. So here another important functionality of the core transport functions is to include QS for the user traffic that enters into the core network. Since the user traffic is being generated from the access side, so the same set of QS parameters which were actually decided upon in the access side are continued in the core side. The gateway is basically an edge router that is responsible for connecting the user equipment to the network equipment on the core side. So there are two types of gateways in NGN, one at the user premises and the other one at the edge of the core network. The primary functions which are provided are including the networking capability. The networking capability is either for intra-NGN that is from the access to the core side or it could be the NGN to NGN connectivity or it could also be the connectivity from the access side to the core and then from that core to NGN networks. The gateway functionality is triggered, invoked or revoked in other words totally managed and controlled by the transport control functions or the service control functions. We can abbreviate them as the TCF or the SCF. The transport control functions are in the transport stratum and the service control functions are in the service stratum. So you see that the gateway functions are controlled by either side. Then we have the media handling functions. The media that is audio, visual or data content of any other form, it is something that needs to be carried over the network. So it is the responsibility of the transport stratum. So the media handling functions are provided in the transport stratum only, not under the transport control function but under the transport function. So the media handling capabilities include what kind of encoding is required or is supported and if there is a requirement for encoding the traffic as well. Because once traffic enters from one kind of user equipment and is meant for another kind of user equipment needs to be transcoded.