 It's going to be an interesting exercise that we look at the individual contributions from the organizations that we've discussed in the previous module. We can skip ITU because ITU is in the leadership role. So the coordination, facilitation, management of the overall activity is to the credit of ITUT. Let's start with the IETF, the Internet Engineering Task Force. Before even engines were conceived and any standardization activity had started, IETF had already standardized the session initiation protocol for signalling. It was meant to replace the signaling standard 7, which is used in the PSTNs and PLMNs. Now with engine documentation with us, it is now an integral part of the engine now. This is an indirect contribution of IETF to the NGN community because otherwise when the ITU started organizing conferences and meetings, IETF had a role there but it was assumed that CIP would be integrated as such. Another important contribution from the IETF is the diameter protocol, which is an advanced form of the radius protocol. This protocol is used for AAA that is authorization, authentication and access for all IP networks, which includes both fixed as well as mobile networks. It was standardized by the IETF in 2003 and the latest version of it goes back to 2012. The diameter was also adopted by the NGN specifically for the database connectivity, which includes the user records. So this is what we can say the prior work that is considered to be a major contribution in the standardization activity. But the biggest role that IETF plays is that the all IP notion, the interoperability which boils down to the availability of IP at layer 3 was standardized by IETF. Not to mention other protocols such as the DNS, the DHCP, the application layer protocols, the transport layer protocols such as the TCP, UDP and the layer 3 routing protocols. So it means definitely IETF is one of the most important players, not surely in the leadership role, which have played a significant role in the standardization of NGN.