Principles and Conditions for Implementation of an ENUM Protocol in France
Abstract of Contributions to the Public Consultation
16 July 2001
SUMMARY OF THE CONTRIBUTIONS ABSTRACT
- The principle of ENUM, as described in RFC 2916 by the IETF, makes provision for associating communication services identifiers with an E.164 phone number. Other relationships could be imagined on the basis of this principle, based on more mnemonic reference systems and broadening services for regrouping identifiers. The ENUM protocol is a way of making the telecommunications and Internet networks interoperable. This must occur within the larger context of a reflection on universal identification solutions among users of convergent networks.
- It is still too early to describe precisely the potential applications of the ENUM protocol whose implementation and use are still being studied. ENUM nonetheless shows promise as a source of innovations. It seems that this protocol should first favor penetration of voice applications into IP and existing convergence services (unified messaging, for example), by making them more user-friendly, before contributing to the emergence of new services. The ENUM protocol is only a conversion device that will have to be associated with other technologies to enable truly convergent services.
- Assessments of the ENUM services market, while these services are not clearly identified, appear to be premature. Consequently, no clientele target should be excluded at this time. However, businesses and technophiles should, a priori, be the first customers targeted. The conditions for implementing ENUM will be the main determining factor influencing emergence of demand.
- The use of phone numbers as a common reference for access to telecommunications services presents an advantage for assimilation of the services based on ENUM, due to its universally widespread use. However, the confidence that will be extended to the validity, the confidentiality and the security of information contained in the ENUM databases will be a determining factor for adoption of services. The market penetration of permanent fixed or mobile IP connections will determine how quickly they develop.
- The ENUM protocol and the system of domain names on which it relies do not, a priori, present technical problems that manifest themselves in service malfunctions based on this functionality. The technical solutions making it possible to optimize service operations should be assessed when experimentation campaigns are to be launched.
- Introduction of the ENUM protocol should not have an impact on applicable regulatory obligations of various communications services, nor application of universal service. In particular, regulatory obligations linked to numbering will have to apply to the ENUM domain name manager. The impact of regulatory and legal conditions to be met in the context of ’ENUM implementation must nonetheless be the subject of in-depth reflection.
- The conditions of competitiveness among the players involved in providing services based on use of the ENUM protocol will depend to a great extent on how responsibility is shared throughout the hierarchical tree structure, especially at Tier 2. Relationships between Tier 2 and service providers will need to be thought through thoroughly.
- An experimental phase whose purpose is to identify obstacles of a technical, regulatory or economic nature to the provision of services based on the ENUM protocol could be launched by ART and the Secretary of State to Industry with extensive participation by the players, once the principles of implementation at the national and international levels have been clearly established.
- The rules for setting conditions for inserting E.164 numbers in the domain naming system must be established quickly and must provide management of ENUM domain names subordinate to management of E.164 numbering. In particular, domain delegations must be made to correspond to delegations of E.164 resources in a willful approach by the entities responsible for these, both at international and national levels. The ITU appears to be the best guarantor of the necessary consistency, but the precise role of the ITU in the implementation of ENUM has not met with a unanimous consensus. A consensus is emerging so that a clear agreement between ICANN, ITU and IAB about the definition of rules applicable to the implementation of ENUM will be found quickly and be included in an internationally recognized document.
- The ENUM reference domain does not appear to be the main challenge, even if the choice of a first-level domain ".arpa" used on Internet for purely technical purposes, does not demonstrate for all an ambition to be neutral. This debate should not obscure the necessity of promoting the uniqueness of this reference domain, the root of the Internet and above all the definition of rules applicable to management of the domain. The definition of these rules is in fact the primary challenge of the framework for implementing ENUM.
- Decisions regarding conditions for implementing ENUM at the national level are premature and must be the subject of an in-depth examination of the consequences of such an implementation. As at the international level, at the national level, unambiguous rules will need to be defined such that delegations of sub-domains follow the logic of distribution of phone numbers. Sharing of responsibilities at Tier 2 seems to be the touchiest point to work out and seems to have an influence on the conditions of competitiveness among the players. There is, in fact, the chance that Tier 2 will be the only one able to provide services based on ENUM. The dominant position that telecommunications operators responsible for assigning number resources could acquire by handling the Tier 2 function must be analyzed as regards the situation of a near monopoly on domain registries, which could be reproduced with ENUM in a model of independent distribution of current phone number managers. In any case, it appears that the relationship between Tier 2 and ASP need to be examined in greater depth.
On 23 May 2001, ART and the Secretary of State to Industry launched a public consultation on the conditions for implementing the ENUM protocol in France. The objective of this call for contributions was to sensitize the contributors and gather their opinions on this project, the numerous challenges of which go beyond the French context. Responses were expected by 12 June. 14 contributions came in, including those of France Télécom, Cégétel, AFNIC, Alcatel, Ericsson, Rénater, Bull, Afutt, Fing, FirstMark, Digital Airways, Prosodie and Devoteam. The widely diverse origins of contributions was such that it was possible to address all considerations evoked in the consultation and compare differing opinions on the most crucial matters. The challenges of Internet governance to which the ENUM project is linked, were addressed in several contributions but are the subject of another debate that we will not address in this abstract.
ENUM type systems are important factors for developing convergence of telecommunications services currently available on the various networks. The contributors agree that communications services transported natively on IP networks will dominate in the medium term. This evolution is still slow today, but will make rapid progress primarily under the influence of two factors: the widespread use of permanent IP connections by users, which will provide such services as calling them when they use IP voice services, and the existence of a universal naming solution that is not limited to a single usage, as is the case with E.164 for telephony, or with DNS for IP services.
II. ENUM: Principle, Applications and Usages
The ENUM standard described in RFC 2916 by the IETF defines a protocol and an architecture based on the domain name system allowing to make communications service identifiers correspond to E.164 phone numbers with a priority number: email, URL address, SIP telephony server address on IP, voice mail, other phone numbers, etc.
This principle led to the following thoughts:
ENUM is seen as a technical correspondence gateway between the switched telecommunications network and the Internet network, but other technical services for grouping identifiers together might emerge. The UCI identifier that ETSI is working on is an example: the individual, and not the terminal, is identified; thus a person can have a unique, perennial identifier (similar to a social security number) and identify his or her correspondent who is using a terminal that is shared with a group (family, business, corporation, phone booth, Internet café, etc.).
In addition, if ENUM is now planning to identify communications resources, it is not impossible to imagine that we might associate geographical coordinates, credit card numbers or any other identifier with those resources. The list of communications resources to which a query regarding a number might be sent, could also be extended to the snail mail address, the physical address or real-time location data provided, for example, by the mobile network.
One contributor considers that ENUM must be considered only as a device for translating between the telecommunications network and the Internet network, constituting a provisional solution to accompany the gradual evolution of networks to "All IP" solutions, after which ENUM would be obsolete. The DNS system implemented for naming on IP networks has demonstrated its capacity to be useable in a worldwide network. Domain names are portable and dynamic by nature (a domain name establishes a link between a name and an IP address at a given instant). Today, however, they remain specific to IP networks and cannot be used in their current structure as replacements for E.164 numbering, hence the short-term interest of the ENUM protocol.
Finally, implementation of ENUM as a naming system based on E.164 numbering seems to give rise to several problems, according to the contributions: first of all, this involves a backward evolution in relation to the design approach of DNS, which aimed to introduce a mnemotechnical name to designate a machine connected to Internet rather than using the figures of its IP address. Subsequently, this solution confers a determining role on the phone number and, by extension, on the operator that holds this number, regarding IP service control for a subscriber.
The ENUM protocol is a means of making a telecommunications network interoperable with the Internet. If the principle of ENUM as described in RFC 2916 by the IETFmakes provision for associating communication service identifiers with an E.164 phone number, other correspondences, based on more mnemotechnical reference system, and broadening the services for grouping identifiers, could be imagined on this principle. ENUM must then be part of a broader reflection on universal solutions for identifying users of convergent networks.
2. Applications of the Protocol
The possibility given to an individual to manage the way in which he or she wishes to be contacted with a simple phone number constitutes, according to the majority of contributions, an interesting and promising approach to new services. However, it seems that ENUM favors the use of existing services first of all before creating new services. Thus, ENUM should be an impetus for development of convergence services that are already known (unified messaging, voice on IP) by giving them greater ease of access, user friendliness and mobility.
The first type of services the most commonly cited by the contributors for short-term use is voice-based applications on IP. More generally, all services that now rely on an E.164 number will potentially be impacted by ENUM. This does not concern, a priori, short numbers or special numbers, which are not included in the ITU’s E.164 recommendation.
The use of the ENUM protocol could, among other things, simplify management of multiple communications resources (fixed or mobile phone, fax, email, etc.) using a "universal number." This number, which is an E.164 phone number in RFC 2916, but which could be any other universal identifier (cf. supra), can be a unique point of access and consultation for a user’s messages in the appropriate format for the terminal that he or she has. Thus, a person could be contacted through any channel, according to his or her availability and the filters and links that he or she has set. An individual, then, will certainly want to have several "universal numbers" for the different spheres of his or her life: private life, professional life, associative life, etc.
As a gateway from the world of telephony to Internet, the ENUM protocol will also provide access to Internet resources from identifiers of telephony (for example, you can visit a company’s Website when all you know is its phone number).
In addition, several contributions point out that if the ENUM protocol contributes to convergence of transport services towards the IP network model, it does not guarantee the convergence of services. The use of numbering and a traditional telephone terminal for applications other than voice or fax transport, requires recourse to other technologies, for example voice recognition, to gain access to Internet services: ENUM by itself cannot enable communication between an email server and a telephone, for example.
Overall, the contributions keep to a very general description of applications tied to the use of ENUM.
It is still too early to describe precisely the potential applications of the ENUM protocol whose implementation and use are still being studied. Nonetheless, ENUM seems to show promise as a means of developing innovations. However, this protocol should first favor the penetration of voice applications on IP and existing convergence services (unified messaging, for example), by making them more user friendly before contributing to the emergence of new services. Finally, the ENUM protocol is only a conversion device that will have to be associated with other technologies to enable truly convergent services.
3. The Market for ENUM Services
Assessments of the potential market and penetration forecasts for services based on the ENUM protocol are difficult and premature, as ENUM is today nothing more than a technical protocol. Reflection on how it will be used is ongoing.
The demand for services will be contingent upon conditions for implementation and the relationship of confidence that the ENUM system may have established.
Services based on use of the ENUM protocol would first be aimed at a professional clientele, already equipped with multiple addresses and communication tools. These services could be used, in particular, in the companies’ internal network or to keep in touch with their roving personnel.
If the widespread need emerges among the public—who can already have several communications resource identifiers and who are becoming more and more mobile—the penetration of this market segment will still be slower and, during an initial phase, be limited to technophiles.
Development of the consumer market will depend to a great extent on the conditions under which ENUM type services will be introduced, which will be as many factors for appropriating this clientele.
Assessments of the market for ENUM services, while these services have not yet been clearly identified, appear to be premature. Consequently, no clientele target should be excluded at this time. However, businesses and technophiles should, a priori, be the first customers targeted. The conditions for implementing ENUM will be the main determining factor influencing emergence of demand.
1. User Assimilation of Services Linked to ENUM
The majority of contributions point out that telephone numbering has the advantage of being widely used and universally understood. It enjoys the benefit of portability and can be entered with a low error rate from all fixed or mobile terminals. It is reliable, as management of phone numbering is governed by clear and stringent rules established by impartial proceedings. A Website URL or email address are more likely to produce errors. Nonetheless, phone numbering is difficult to memorize, especially if numbers have to get longer to meet expanding needs, and does not necessarily establish a one-to-one relationship between a number and a person.
Others suggest that the unique key serving as a common reference base in the ENUM protocol for access to a wide variety of communications services (the phone number in this case) establishes a stronger relationship between a number and a person. It will consequently be more difficult and costly to change numbers. In this context, other identifiers besides the phone number could be used. A reference system based on the name of the individual, for example, would be a factor of assimilation. Nonetheless, one contribution evokes the debates now underway within the ICANN on internationalization of domain names that show that the use of characters in a naming system is sensitive to cultural differences and can consequently not be universal, hence the interest that might be held by having recourse to E.164 numbering as a common reference system.
Many contributions point out that user assimilation of ENUM and services that grow out of ENUM will depend essentially on the conditions for implementation: that the added value of services is well understood, ease of use and cost. The possibility left to the user to easily insert his or her number—or not—in the ENUM naming tree, to access data associated with the domain name, the confidence that will be given to the validity, the pertinence and the confidentiality of information will have a very important impact. As is the case for measures taken to prevent risks of rerouting traffic flow unbeknownst to the supposed recipient or sender.
The rate of adoption of permanent fixed or mobile IP connections will also be a determining factor for development of ENUM services. As is the case for implementation of the portability of a personal number assigned to a user indefinitely.
Assimilation will probably be different according to whether services using ENUM are new or not and whether they compete with existing services. For example, the economic gains that can be made on telephony could be a significant assimilation factor both for businesses and private parties. The potential revenue loss for operator, on the other hand, could bring about a lack of enthusiasm for the promotion of such a technology.
Using phone numbers as a common reference system for access to telecommunications services presents an advantage for assimilation of services based on ENUM, due to its widespread use and universal recognition. And yet, the confidence that will be given to the validity, the confidentiality and the security of information contained in ENUM databases will be a determining factor for adoption of the services. The penetration of permanent fixed or mobile IP connections will determine the rate at which they grow.
The ENUM in itself and the mechanisms of DNS, which is considered to be a robust system, do not seem, a priori, to present technical problems likely to manifest themselves in service malfunctions based on this functionality. Still, for nearly all contributions, the capacity of the centralized, hierarchically organized DNS architecture to handle queries generated by services demanding transport of information of good quality in real time will need to be assessed at each level of the DNS architecture, according to the load and level of availability required by each service.
With the absence of precise data on ENUM applications and the extent of their penetration, contributors are not able to be more precise. Several contributions still articulated some recommendations regarding implementation of ENUM to prevent technical difficulties that could have an impact on the smooth running of ENUM services.
The databases that will host the files that store information to match up phone numbers and URLs must be sized appropriately. In addition, a distributed server architecture seems to be preferable to a centralized architecture for query distribution.
It also seems important to define the conditions for accessing ENUM gateways: when to query the ENUM database; is it necessary to launch a query every time a call is made to an E.164 subscriber, even if it is not for the purpose of putting through a phone call? Is it possible to avoid mobilizing unneeded telephone circuits? What modifications to the structure of the telephone network will be necessary to meet the demands of the growth of signal traffic? ...
Finally, the division of figures corresponding to country codes into several sub-domains (.3.3 instead of .33) could manifest itself in an unneeded load on DNS servers.
The ENUM protocol and the domain names system on which it relies do not, a priori, present technical problems that might manifest themselves in malfunctions of services based on this functionality. The technical solutions that will provide for optimizing the running of services will need to be assessed in the experimentation phase.
3. Impact of ENUM on Market Players
3.1. Regulatory Considerations
The contributions that addressed regulatory considerations express the wish that regulatory obligations that are applicable to the various communications services are not impacted by introduction of the ENUM protocol. As an ENUM domain name is considered as another way of presenting a phone number, its manager must have the same regulatory obligations that are applicable to the various communications services as those of a traditional telephone services operator. ENUM must not interfere with the continuity of universal service.
The impact of regulatory and legal conditions to be adhered to in the framework of ENUM implementation must nonetheless be the subject of a more thorough reflection. The obligations that might apply to ENUM service providers concern, in particular: the portability of registration, the update of information, availability constraints, confidentiality of information, protection of personal data, authentication of data and contribution to universal service.
Regarding the lawful interception of calls, it is the use of IP networks that can make it difficult by requiring probes that get very close to the subscriber and not just into the network core.
The introduction of the ENUM protocol should not have an impact on the regulatory obligations that are applicable to the various communications services, nor on application of universal service. In particular, the regulatory obligations linked to numbering will need to apply to the ENUM domain name manager.
The impact of regulatory and legal conditions to be adhered to in the framework of ENUM implementation must nonetheless be the subject of a more thorough reflection.
3.2. Conditions of Competitiveness Among the Players
The contributors consider that the ENUM protocol in itself has no influence on adherence to the principles of free competition. It is in its implementation, for the provision of services, that these principles need to be evaluated.
The conditions of competitiveness among players involved in providing services that rely on the use of the ENUM protocol will depend to a large degree on the sharing of responsibility that will be introduced at all levels of the hierarchical tree structure and, in particular, at Tier 2 (cf. IV.2.1). It is important to be watchful so that Tier 2 is not the only level that can provide ENUM-based services. The relationships between Tier 2 and the potential ENUM service providers will need to be studied.
Several contributions suggest, on this subject, that drawing a distinction at this level of management of the DNS server in which the ENUM name is registered—the ENUM database containing the records of communications services—would contribute to reducing the dominant positions for the provision of ENUM services that operators that are the keepers of these numbers could take. This distinction should manifest itself in the definition of ENUM gateway interfaces.
The conditions of competitiveness among players involved in providing services that rely on the use of the ENUM protocol will depend to a large degree on the sharing of responsibility that will be introduced at all levels of the hierarchical tree structure and, in particular, at Tier 2. The relationships between Tier 2 and service providers must be the subject of in-depth reflection.
The necessity of an experimental phase in France is acknowledged by numerous contributors. This phase would focus more on services than on the protocol itself. Any technical problems of this protocol would be resolved within the IETF. It could at the same time allow for validation of the technical functioning of services, but above all, their pertinence for the regulatory obligations related to use of E.164 numbering. This would also make it possible to enter into a reflection on the new services and the economic conditions of providing these services to the public, while assessing their suitability to market demands.
It could be launched and coordinated by ART or the Secretary of State to Industry.
Nonetheless, at least one contribution emphasized that it seemed premature to launch such an experimentation phase as long as the responsibilities of the various players have not been established at the national and international levels.
An experimental phase the aim of which is to identify the obstacles to provision of services based on the ENUM protocol of a technical regulatory or economic nature could be launched under the stewardship of public authorities with the wide participation of the players, once the principles of implementation at the national and international levels have been clearly established.
IV. Architecture of ENUM Services
The ENUM principle involves using traditional phone numbers managed in each country by a national regulatory authority, and the architecture of the domain name system put into place on Internet and managed by self-regulated proceeding by private players. The ENUM project is situated, then, at the meeting point of two worlds with different rules and different players, and is worthy of close scrutiny regarding the conditions of its implementation at both the national and the international levels.
1. International Implementation
1.1. Insertion of E.164 Numbers in the DNS
All contributors emphasize the need to provide ENUM domain name management that is subordinate, at all levels, to management of E.164 numbering. ENUM domain names, in reality, entail a different presentation of E.164 phone numbers. Consequently, it is necessary that the procedures for inserting numbers in the DNS provide the means to ensure a flawless consistency between E.164 numbers and ENUM domain names. Application of the principle of technological independence must be such that there is no difference for the user between using an E.164 phone number via a phone network or using it through a gateway and an ENUM domain name.
In particular, the introduction of ENUM must not disturb the conditions for managing numbering resources or the principles on which they are based: transparency, free competition and lack of discrimination. The rights and duties of the players in relation to numbering resources must be taken into account when drawing up these procedures.
Clear rules establishing the conditions for delegation of the reference domain for ENUM and sub-domains at each level of the naming tree, must provide the means to ensure this consistency. They must be defined first at the international level in concert with all of the involved players: ITU, ICANN and IAB.
At the international level, a majority of contributions consider it desirable for the IUT to coordinate implementation of ENUM and to handle administration of the reference domain (Tier 0). The ICANN is considered to be an organization that is too young, too fragile, with no regulatory power, and too dependent on a single government to handle this coordination. The ITU, an entity that grows out of the United Nations organization, enjoys the benefit of years of experience with the rules for managing the international numbering system and can be a guarantor of neutrality. In this capacity, the ITU appears to be the best guarantor of consistency between E.164 numbers and ENUM domain names. Technical management of the domain could be handled by the organization designated by the ITU in concert with the ICANN.
Other contributions consider that it is not necessary for the ITU to have an operational role in implementation of ENUM. First of all, by subordinating ENUM architecture to numbering architecture, such a choice could inhibit evolutions that might use other identifiers. Putting forward compliance to subordination to the rules for assigning numbers for recording ENUM names, as well as instilling penal disincentives on ENUM service providers, would suffice, in the assessment of these contributions, to ensure consistency in procedures for the insertion of numbers. An organization growing out of the ITU and the ICANN could provide a compromise solution.
Finally, the majority of contributions consider that sub-domains should not be delegated to the technical manager unless the corresponding entity that assigns E.164 resources asks for this under the conditions that it defines. The sub-domains corresponding to the country codes of the ITU, in particular, must adhere to this rule. The managers of national numbering plans should ensure the consistency of the insertion of resources in numbers that are under their responsibility.
At the national level, this same scenario could be followed in tandem with the national numbering plans.
The rules that establish the conditions for inserting E.164 numbers into the domain name system must be established quickly and ensure management of ENUM domain names subordinated to management of E.164 numbering. In particular, domains must be delegated in concert with the delegation of E.164 resources in a willful approach by the entities responsible for these resources at both the national and the international levels.
The ITU appears to be the best guarantor of the necessary consistency, but its precise role in the implementation of ENUM is not the subject of a unanimous consensus. A consensus is emerging for a clear agreement between ICANN, ITU and IAB so that definition of rules applicable to implementation of ENUM will be found quickly and be included in an internationally recognized document.
Clear, transparent rules precisely defining delegations and responsibilities of each player are an essential element of the future device.
1.2. Choice of a Top-Level Domain
Several contributions emphasize that ENUM domain names should not be dialed by the users of services for which the translation of numbers into domain names, handled by the equipment, would be transparent. The choice of the top-level domain therefore has no technical implications and no impact on implementation of ENUM services. It is more of a policy decision. On this matter, IAB’s proposal to use the domain "e164.arpa" indeed establishes a dependency by ENUM systems on the ".arpa" domain and on the IANA, which manages it, but this domain is used for needs of a purely technical nature, such as reverse resolution of IP addresses and seems to be appropriate for some.
On the other hand, this choice is considered by some to be an abandonment of sovereignty, with risks to public and individual liberties. It could also grant the administrator a monopoly, reflecting the dominant status acquired by Verisign in managing the domain ".com." This leads numerous contributors to suggest using the domain ".int" dedicated to international activities or creating another top-level domain (".tel," ".itu," ".enum" or ".mume" for multimedia), supposedly more neutral and dedicated to the telecommunications sector. A domain free from influence by a single government would determine, for some, development of ENUM type services.
But certain contributions emphasize that the domain chosen will inevitably depend, like the entire DNS system, on the root server of the Internet (a.root-server), managed by the firm Verisign/NSI under the ultimate authority of the US Department of Commerce. What is more, it would take time to create a new TLD.
Finally, several contributions suggest that the top-level domain in which the numbers corresponding to the phone numbers will be inserted must be chosen on the basis of a consensus among all the countries, under the stewardship of the ITU, to which administrative responsibilities could be given. This agreement must be devised with an eye to avoiding any break in the implementation of ENUM services in a system that is public and universal. Any delays would favor the emergence of alternative solutions that would constitute established positions and be sources of confusion.
Regarding technical management of the ENUM domain, the contributions suggest that the decision to delegate technical management of the domain "e164.arpa" to RIPE NCC appears today to be premature, as there is no agreement among the various players (ICANN, ITU, IAB) on the choice of domain to use. In addition, without eliminating RIPE NCC from the running, the contributors consider that the current missions of this non-profit association are situated outside of the realm of naming and numbering that concern ENUM. In any event, clear conditions of administration and registration procedures must be established before delegation of technical management.
Regarding competing domain names, all contributions consider that they would constitute a harmful source of confusion in relation to adoption and recognition of a universal system with clearly defined rules, a pledge of transparency for players and users for fair competition and consistency. It would be suitable to avoid the sort of situation we are in now, in which roots competing with the DNS currently used in Internet are emerging. It appears necessary for governments to take appropriate measures to avoid the emergence of alternative naming systems that are not interoperable. Nonetheless, it does not seem necessary to prevent the existence of ENUM type systems in a market dynamic of innovation, from the moment that a public and universal service recognized by the ITU is put into place. The matter of choosing a domain name then becomes secondary to the necessity of promoting a single reference domain and a delegation system subject to rules that are clearly defined at both the national and international levels.
The ENUM reference domain does not appear to be the primary challenge, even if the choice of the top-level domain ".arpa," used on Internet for purely technical needs, does not demonstrate an ambition to remain neutral, in the eyes of some. This debate should not obscure the necessity of promoting the uniqueness of this reference domain and the interoperability of Internet, and above all, the definition of rules that apply to its management. The definition of these rules is in fact the primary challenge of the framework for implementation of ENUM.
2. Implementation at the National Level
Certain contributions emphasize that any decision affecting implementation of ENUM in France seems premature as long as an agreement on the conditions of implementation at the international level has not been reached. In addition, an agreement among the national players on a clear scheme for sharing and delegating responsibility constitutes a prior condition to deployment of this protocol.
Nonetheless, the contributions listed some leanings regarding how ENUM could be implemented in France.
The sharing of responsibilities at the national level, in the assessment of the contributions, will have an impact on the success of ENUM. At the national level, this sharing affects Tier 1 and Tier 2 in the layered model developed in the call for contributions. It will determine the confidence that prevails between the entity that assigns the ENUM name and that of the corresponding number. The risk is that a service based on the use of ENUM can be provided only by Tier 2.
As at the international level, several contributions suggest that at the national level, sub-domains should not be delegated to the administrator unless the corresponding entity that assigns E.164 resources asks for this under the conditions that it defines, and this in compliance with the logical system for distributing phone numbers followed all the way through to the end customer.
Thus, for Tier 1, the governments should designate the entity charged with administration of their national numbering plan to manage the domain corresponding to their country code and ensure the consistency of insertion of resources in numbers for which they are responsible.
In France, the Telecommunication Regulatory Authority (ART), which is responsible for the numbering plan in metropolitan France and overseas departments, could handle administration of the domain corresponding to the country code in France. Technical management of the domain could be entrusted to another organization. AFNIC, registry of the country-code-top-level domain ".fr," has applied.
For Tier 2, some contributions suggest that operators who hold a license manage the domains corresponding to numbering resources that are allotted to them, that is, that they fill the Tier 2 role. They could thus easily feed the ENUM databases and ascertain the identity of their customers to whom a number had been assigned. In addition, this solution would make it easier to update databases when a subscriber was added or removed, and avoid acts of cyber-piracy.
This distribution is contested by other contributions. These contributions consider, on the one hand, that endowing public authorities with a dominant role in implementing ENUM could deprive some countries where Internet use is controlled or the means of launching this project would be lacking, and on the other hand, that this way of sharing would confer a dominant position upon historically established telecommunications operators, who manage a large share of E.164 phone numbers. There is indeed a risk that the operator in whose databases the domain name ENUM were registered, and who could be competing for the provision of other services, would be reticent regarding introduction of corresponding addresses.
Certain contributions suggest that by assigning responsibility as Tier 2 manager independently of those assigning numbering resources, in that this would give free rein to registries of generic domain names, the establishment of dominant positions would not be prevented. Thus, the initiatives of companies like Verisign, administrator of the domain ".com," or Neustar, administrator of the numbering plan for North America and co- administrator of the domain ".biz," to register domain names such as "enum.org" or "enumworld.com," lead us to believe that they stand ready to take a share of the market likely to grow up around ENUM, a dominant position analogous to the position they hold in the domain name registration market.
Some contributions suggest a few paths for ensuring that Tier 2 will not be the only one able to offer services based use of ENUM. Thus, if the phone number of a user were recorded in the databases of the operator that provides his or her phone service, the choice of providers of services other than telephony services should be, for its part, unrestricted. Toward this end, it is important that access and parameter settings for the list of URIs corresponding to various possible destination addresses, be left to the subscriber, with appropriate identification mechanisms. This is essential to letting subscribers manage access to their communications resources as a function of their own situation. The definition of ENUM gateway interfaces could make provision for this possibility. In all cases, it appears that relationships between Tier 2 and ASP need to be given greater depth.
Decisions regarding conditions for implementation of ENUM at the national level are premature, and their consequences need to be examined in greater depth. As at the international level, at the national level unambiguous rules will need to be defined so that delegations of sub-domains will adhere to the logic of distribution of phone numbers. The sharing of responsibilities at Tier 2 seems to be the touchiest, due to the potential influence on conditions of competitiveness among the players. There is indeed a risk that Tier 2 will be the only one able to provide services based on ENUM. The dominant position that telecommunications operators responsible for assigning number resources could acquire by handling the Tier 2 function must be evaluated in regards to the situation of near monopoly on domain registries, which could be reproduced with ENUM in a model for independent distribution of the current phone number managers. In any event, it appears that relationships between Tier 2 and ASP need to be given greater depth.
The contributions consider that registration procedures must take into account considerations regarding protection of personal data, as all information in DNS databases are, a priori, in the public domain and can be accessed and consulted by anyone.
In the case of ENUM, authentication mechanisms will have to control access to information in ENUM databases, which can be compared to Whois databases for domain names.
Set-up of ENUM must take place starting now on the basis of a concerted effort by all players at all levels of the ENUM hierarchical tree structure, in particular, the control by end users on the insertion of their phone number in a DNS domain (the one chosen for a universal ENUM service and for alternative ENUM type services in competing roots) and in related data that concerns them.
No contribution precisely addressed the cost of implementation and maintenance of ENUM databases, nor how this cost would be passed along to end-users.
ASP = Application Service ProviderDNS = Domain Name System
IAB = Internet Architecture Board
ICANN = Internet Corporation for Assigned Names and Numbers
IETF = Internet Engineering Task Force
ITU = International Telecommunication Union
RFC = Request For Comment
SIP = Session Information Protocol
TLD = Top-Level Domain
URI = Uniform Resource Identifier
URL = Uniform Resource Locator
UCI = Universal Communication Identifier
