 Now that we all agree that the managed delivery service is the way to go in NGN for effective control and better delivery of services, let's look at the options we have with regards to service provisioning. So we are going to look at the service types and how these services are invoked or are not invoked. To begin with we say that the service types in NGN through MDS are available depending upon certain characteristics. These characteristics are are these services subscription-based or non-subscription-based? Are these services based upon some kind of explicit request kind of mechanism and is there a control process through which these services can be negotiated between the third party and the engine operator. On the basis of it we can look at three different viewpoints that is subscription-based viewpoint in which we have subscription-based services and non-subscription-based services. The subscription-based services are actually in turn connected to all three service types that is what kinds of services can be requested from the network. We can have an always-on service, we'll briefly talk about this. We have pre-scheduled service and we have on-demand service. Now the subscription-based services are connected to all these different three service types whereas the non- subscription-based is only connected to the on-demand service. Then we have the control view that is once we have relationship or business relationship between service providers as third parties and the NGN as in architecture. So we have either controlled process or we have no controlled process. Let's look at these in detail now. The subscription-based service types actually are the ones which exhibit some kind of regular behavior. It is you can say a regular behavior in terms of temporal behavior that is it's a timed behavior. Examples are VPN connectivity that users would like to subscribe to. We have the leased lines, we have the network-controlled real-time services like voice over IP, IPTV, etc. So these kinds of services have something in common that is from the user's perspective they are related to some kind of repetitive behavior from the user. So user once subscribes to these are is going to stick on with these. Then we have non-subscription-based services. These are basically the user demands which do not have prior subscription requirement. So whenever a user feels like watching a video known as the video on-demand service or bandwidth on-demand service or when a user wants to establish a video call like video phone or a multi-party conference call. So these are these don't need explicit subscription. Then we have the request view point. Request view point actually means that is the user going to make an explicit request or the request is assumed to be already there. So when a user is available online we say that the user is going to get a service all the time whenever a user is online and we say the user is going to get always on service. The moment a device attaches to the user device attaches to the network the user becomes online and the service starts getting provisioned. For instance billing is a service which is based on always on service type. So when the user is not connected the service is automatically terminated or disconnected. Then we have the pre-scheduled services. Now pre-scheduled services are the ones which are time-based for example calendar annual calendar-based services which get invoked on a certain time of a certain day. So this actually can only happen if user and the third party have already agreed on this service provisioning in the form of some contract. Then we have the on-demand service. The on-demand service is the one which is only triggered by the user on-demand. Now this is similar to the applications like video on-demand, bandwidth on-demand etc. So this is yet another view point known as the service request view point. Now if we just combine all these and we realize that these are all intertwined or interlinked with each other. So we can expect that we are now going to look at the third link that we talked about in the MDS business model. That is whether third party takes part in a service provisioning process or not. It is based on the control process. So the control process comes through the participatory role of the service provider and the NGN. So if the third party takes part in the service processing and service delivery, so it means that there's an agreement between third party and NGN operator. So all these services including always-on, pre-scheduled and on-demand can be realized if there's a direct relationship between the third party service provider and the NGN operator. If there is no participation as such, in that case we don't expect the on-demand service to be provided because the on-demand service can only be provided if there is active interaction between the service provider and the third party. The other services like always-on service and the pre-scheduled service once agreed can always be provided without the participation or the relationship between the third party and NGN.