OECD: ENUM: CONVERGING TELEPHONE NUMBERS AND ADDRESSES IN NEXT GENERATION NETWORKS

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The following is an excerpt from the OECD report on converging telephone numbers and addresses in Next Generation Networks: Main points This paper provides an overview of developments in numbering, naming and addressing in the context of Next Generation Networks (NGN) with a focus on ENUM. ENUM comprises a diverse set of standards and non-standardised mechanisms for transforming public telephone numbers into unique domain names.  The main conclusions of this paper include: Numbering, naming and address translation Telephone numbers will remain as key identifiers for telecommunication services for the foreseeable future, despite the use of IP and the surge of new address schemes in NGN. Increased use of ENUM mechanisms could even prolong the lifespan of telephone numbering. Convergence and the shift to IP will accelerate ‘number detachment’ and will increase the pressure on regulators to further augment the flexibility of numbering plans, broaden the uses for existing number ranges, extend the possibilities of personal allocation to end users, and consider portability of elephone numbers between services. The uptake of ENUM as a non-standardised mechanism for translating telephone numbers to other addresses can first of all be seen in the VoIP interconnection market. In particular new VoIP carriers use Carrier ENUM in combination with SIP as an alternative for SS7, the Signalling System used in the traditional PSTN environment. The uptake of Carrier ENUM can also be seen in newly developed standards for the architecture of NGN, where it is the preferred but not only option to perform the translation function of telephone numbers to other addresses. ENUM, when used in networks as a mechanism for translating public telephone numbers into other IP-based identifiers, will enhance interoperability between the existing public switched telecommunication environment and new Internet Protocol based environments, therefore helping providers and users continue to use telephone numbers in NGN. User ENUM and Infrastructure ENUM Privacy and security risks are mainly associated with these public versions of ENUM, and are the result of the public exposure of data in the Internet: personal data in the case of User ENUM and interconnection data in the case of the (proposed) Infrastructure ENUM standard. For User ENUM improved authentication mechanisms preventing misuse of data (spoofing, ID theft, etc.), such as DNSSEC and other solutions, are the most effective tools to overcome these risks. The deployment of User ENUM is limited to eight countries and characterised by slow growth, and there are no indications that this growth will suddenly accelerate. While some argue that there is no viable commercial market for User ENUM, advocates argue that it may still take some time for the right conditions for User ENUM to prosper. Finalisation and deployment of the Infrastructure ENUM standard will depend on discussions between IETF and ITU. Meanwhile continuing growth can be expected in the use of non-standardised variants of ENUM in the market place, such as Carrier ENUM. VoIP interconnection The combination of IP, DNS and the ENUM mechanism is, amongst other solutions, an effective tool for market parties to set up databases with VoIP interconnection data and exchange this information with trusted partners. Increasingly telecommunication providers are grouping into federations, agreeing on a shared approach for VoIP interconnection and enabling settlement free peering between themselves. Connectivity between federations, the bridging of the ‘VoIP islands’ is currently a significant challenge for the market, as centralised data for the termination of VoIP calls are lacking. This federated model might introduce competition and interoperability risks in the VoIP market, if providers outside federations face barriers to interconnect. An open, fair and competitive communications market could therefore benefit from transparent and non-discriminatory conditions for access to VoIP interconnection data, in analogy to the access to number portability data in most OECD countries. Number portability Mobile operators and other market parties have expressed the need to adapt number portability arrangements to incorporate VoIP interconnection data. The ENUM mechanism is a useful tool to set up these databases segmented on national lines, therefore becoming an issue of national scope. Depending on national conditions and specific regulatory provisions on number portability, regulators could co-ordinate or co–operate with industry in setting up ‘next generation’ number portability platforms.

By OECD: Working Party on Communication Infrastructures and Services Policy. Published January 2010.

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