 Starting from the translation of a dial number to the e164.ARPA domain, the enum format to how the traffic is actually sent to the network on the transport stratum, it would be interesting to have an insight into how the routing model is laid in the engine architecture. For that we'd have to look at how the address resolution takes place and how the routing is then onwards performed. The address resolution starts with the processing of the dial string. The details of it are given in the next slide once we look at the flowchart but let's quickly review it here as well. Now the dial string is sent as a request URI to the home network. The home network essentially implies the IMS for processing this request. The format could be if it is let's say a watch over IP connection then it could be user at example provider dot net or if it is a telephone number that is based on the enum format then it could be something like plus three at nine number at the rate example provider dot net and user is the IP phone. So what is the result of this translation? This translation or resolution results into a routable SIP URI that is now ready to be sent into the network for delivering data in any form to the destination. Let's look at it as a flow of information. The address resolution starts with the dial string. The dialing process is then used to translate E.164 either into a telephone URI or into a SIP URI depending upon which URI is used either infrastructure enum or other SIP databases are referred to. After that routable SIP URI is extracted by appending the domain name and then the root determination takes place that involves the DNS, the routing database and the other entities such as the routing tables. After the root selection is done then the routable SIP URI is once again referred to if it is a query that is sent for a destination within the domain or outside the domain or if it is for a mobile user or for a static user in any network then corresponding entities including the DNS and the home location register etc. are consulted. So routing is essentially an activity that takes place after the address resolution. The result of address resolution and a routable URI formation helps us to forward the packet or the query or the response, any format to the IMS in the same domain if the target is within the same domain either it is meant for a PSTN or PLMN network in that case this particular request is sent to corresponding gateway or if it is from one NGN to a completely different administrative controlled another NGN. Since the root selection process is performed on the basis of the target home domain so it is quite easy to understand the domain name resolution that works in conjunction with the IP address lookup. So the nodes in IMS actually are that we already are familiar with that is serving call session control that establishes the link between the calling party and the call party the DNS and the routing database. So we can summarize the end to end routing process starting from the service application that is the user sharing the profile parameters to activate or use the service we have certain options that is if it is an internal routing scenario or if it's external routing scenario if the traffic is going to be sent on to the next hop or if it is going to be sent to the default or the gateway router then it also has to respect if certain routing policies such as load sharing, border gateway protocol kind of policies are implemented and then if it is internal or external after that the IP address resolution takes place and eventually the transport layer is invoked. The transport layer invocation results into the choice of the next hop node or the gateway and the IP internet working policy is enforced finally after the routing is done then at the individual router or intermediate device level packet forwarding takes place.