This Recommendation gives a general overview of phase 1 of the evolution of next generation networks (NGNs) in terms of service and capability requirements, as well as a capability framework.

The Recommendations for NGN evolution will be developed phase by phase. This Recommendation addresses phase 1 of NGN evolution. The key objective of NGN evolution phase 1 is to satisfy any additional requirements with respect to NGN capability set 2 [ITU-T Y.2007], for the support of network intelligence, virtualization and programmability for services and applications for humans and things. In particular, this Recommendation provides the service and capability requirements as well as the capability framework of NGN evolution phase 1. Relevant NGN evolution deployment scenarios are addressed in Appendix I.

As this Recommendation addresses the overall requirements and capabilities for NGN evolution phase 1, and in order to avoid the overlap or inconsistency with the relevant Recommendations related to NGN evolution, this Recommendation makes reference to the relevant Recommendations, as appropriate.

Along with the introduction of the key enhancements mentioned above, Appendix II provides some additional potential requirements of NGN evolution phase 1 which need further study and are not currently addressed in specific Recommendations related to NGN evolution. This could be used as background information to assist the future development of Recommendations related to these potential requirements and corresponding capabilities.