Digital Regulation Platform

Numbering: NNAI resources in the digital age



As technology and services have changed over the past few decades, the use of numbering, naming, addressing, and identification (NNAI) resources have continually evolved. The introduction of direct international dialling, and of mobile communications are the cornerstone of the evolutionary path that now continues into the digital age. Even more influential is the changing environment – the rules of use and the actors within those rules – in which NNAI resources are evolving.

The introduction of competition has brought more operators and service providers, and the introduction of regulators[1] has introduced independent oversight of the use of NNAI resources.

It is against this background that the use of NNAI resources must be viewed.

The role of the regulator in managing and allocating NNAI resources for digital services

With the introduction of digital services, the role of the regulator in managing NNAI resources will be determined by the legal framework of the country in which the regulator exists. The legal framework should establish the general principles by which the regulator should act, for example, requiring the regulator to ensure that there are sufficient NNAI resources available to meet industry needs. A further example of a general principle is the responsibility to protect consumers, including when using NNAI resources. The regulator can also be instructed by the national framework to take certain actions, such as charging for NNAI resources, either on a cost recovery basis or as a means of managing the availability of resources, or being required to provide a national numbering plan.

In reality the realization of these general principles varies between countries. The variations can exist depending upon the extent to which a country has introduced competition, or established the legal framework, and the form that the legal framework has taken within the national environment. In the digital age, one obvious example of the variation is the approach that has been taken to over-the-top (OTT) services, and the access of such services to NNAI resources.

The approach taken to OTT services within a country, especially for those OTT services that duplicate voice telephony services to a greater or lesser extent, is impacted by factors such as the degree of competition in a country, and the extent to which the government relies on revenue from telecommunications (either as part owner or through taxation) within the national context. This influences the actions that a regulator can take.

The utilisation of national NNAI resources for machine-to-machine (M2M) and Internet of Things (IoT) capabilities and services is another area where the application of general principles governing the role of the regulator can be realized in various ways. M2M/IoT is now the fastest growing area of the digital age and its impact upon the demand for NNAI resources should not be underestimated. Like OTT services, the approach taken by the regulator will be determined by a number of factors. While some of these factors have been identified previously, the development of proprietary technology that uses its own private NNAI resources that are not the responsibility of the regulator also have an impact. In such cases, it is likely that deployment of M2M/IOT capability using such private technology and its associated identifiers (if they exist) may reduce the demand for NNAI resources that are the responsibility of the regulator.

The examples of OTT services, especially related to voice services, and M2M/IoT capabilities show the need for both flexibility and adaptability in a timely fashion by the regulator in managing NNAI resources.

Procedures for allocating NNAI resources for different services

The use of NNAI resources that are the responsibility of the national regulator have been evolving over the past 60 years. As technology was introduced that supported direct international dialling, there was a need to support communications between “subscribers” (as they were traditionally called) in fixed geographic locations in different countries and was achieved by adapting the use of telephone numbers that allowed users to identify the country through the assignment of numeric identifiers. This capability built upon the national capability of “subscribers” to “automatically” or directly, contact other “subscribers” nationally.

Further technological evolution introduced handsets that no longer required fixed wire connectivity. This capability brought with it the need to develop NNAI resources, such as the international mobile subscription identifier (IMSI) that allows operators and networks to determine where the handset is and where calls had to be directed. The IMSI replaces in a mobile network the routing function that telephone numbers performed in the fixed network. The introduction of the IMSI is a good example of the evolution of NNAI identifiers, from concept to implementation, and from specification to utilization involving operators, networks, and regulators.

As the technology evolved so has the mechanisms for managing NNAI resources. At the same time as mobile communications were emerging, many countries introduced independent regulators and the responsibility moved away from operators. As a result, mechanisms were introduced to ensure that required changes to NNAI resources met both commercial requirements (the introduction of competition, the emergence of new services, and so on) and regulatory requirements (e.g. ensuring sufficient NNAI resources to meet demand). To meet these often-competing requirements, regulators developed the means and mechanisms to manage NNAI resources.

The means and mechanisms used by regulators are in general the same, by identifying a need, undertaking a consultation with relevant stakeholders, identifying the next steps, and implementing them. However, the manner in which this is achieved varies between countries. The management of NNAI resources, while similar on one level to the role of the regulator, e.g the general principles associated with the role including making NNAI resources available, also varies between countries. These variations in management reflect both the high-level regulatory and legal framework, and the decisions taken previously in managing NNAI resources.

The way in which national regulators assign NNAI resources to an OTT service provider illustrates these differences. For those countries that have given OTT service providers equivalent status within the national regulatory and legal framework, there is access to numbers. In contrast, where equivalence is not given, then no NNAI resources are assigned to OTT service providers. This is influenced by the status of the OTT service provider within the national context.

The issues that the regulator needs to consider in assigning NNAI resources to M2M/IoT are the definition of M2M/IoT services, and whether demand for NNAI resources be met from existing resources, or whether new NNAI resources need to be implemented. The factors that can influence the decisions taken by the regulator include:

Whichever way a regulator chooses to answer these questions will depend upon decisions that have previously been taken on other developments that are associated with managing and deployment of NNAI resources as well as the legal and regulatory requirements that are set out. That said, the means by which the resources are managed, both on a day-to-day basis and to meet evolving needs and requirements should be flexible and responsive. There is no single answer as to what a national numbering plan should look like, but there are general principles and best practice that exist, such as having generic mechanisms and procedures, having rules as to who can be assigned NNAI resources and in what circumstances, and using the mechanisms to determine how the existing rules can be adopted to meet emerging trends and requirements.

The related work of ITU-T: a brief overview

Since the 1960s, the evolution of the use NNAI resources in a national context has been mirrored by the evolution of the definitions of use of NNAI resources being specified by the International Telecommunication Union (ITU). As with the emergence of numeric designations for countries, first for telephony, then for packet-switched data networks, and subsequently for mobile networks, the ITU has a history of assigning resources to the national environment. This allowed for member states to assign resources to entities within their jurisdiction.

In the 1990s, the focus on satellite communications, independent of any one jurisdiction, gave rise to the demand for NNAI resources. So began the specification of NNAI resources that were directly assigned by the ITU to entities other than member states.[2] As the discussion over the criteria for assigning NNAI resources for satellite services began, so terrestrial entities saw the potential, especially for services that were international, that would require NNAI resources from various countries and that did not fit into the current NNAI resource schemes. These assignments for networks were established and the criteria covers the various aspects of NNAI resources that are often associated with services in modern communication.[3]

In parallel to the development of the network codes, the ITU began to develop service definitions for the non-geographic services that were having national NNAI resources allocated, such as toll-free numbers. The service definition recognized that the use of such numbers could be international and allowed for the use of national freephone numbers to terminate at points outside of a country. It was also recognized that there were some entities that had many such resources and for whom one global NNAI resource would be of benefit. In parallel to allowing the use of national NNAI resources for such services to terminate overseas, the ITU developed a global resource that could be used as an alternative by an entity rather than having to use multiple national numbers. These global resources are directly assigned to the entity concerned.

Other directly assigned resources for other non-geographic services were developed at the same time, including shared cost and premium rate numbers. These directly assigned numbers are available today and reports on the status of the numbering resource is reported to the relevant ITU-T study group for information.

In recent years, the demand for global resources for M2M/IoT use has developed apace. The requests that have been seen for NNAI resources reflects development of the technology and commercial offerings. Requests for directly assigned global NNAI resources for M2M/IoT has required a reconsideration of the criteria by which the ITU assigns such resources.

One of the main drivers for the reconsideration of the criteria has been the need to ensure that assignment of a global resource could not be used to provide bypass of national regulation, a situation originating from the view of some countries that OTT service provision is fraud. As with national regulation, the ITU criteria has evolved over time and, in consultation with stakeholders, has arrived at a process that can contribute to the more rapid direct assignment of NNAI resources.

The reference to the ITU criteria needs clarification. Although the responsibility for assigning all of these global resources rests with the Director of the ITU’s Telecommunication Standardization Bureau, it is the ITU members who determine the rules and provide the advice through a specialist and technical study group on operational aspects.

The development of such criteria continues, and the discussions within the study group demonstrate the ongoing needs for NNAI resources. Much has been written about the use of alternative NNAI resources, other than those under the responsibility of national regulators, and while such use has been increasing, based on the demand for directly assigned NNAI resources, as a reflection of national NNAI resources, it is not diminishing.


  1. The term regulator is used to define the entity to whom the government has given authority to manage NNAI resources nationally, be it a government department, ministry, or an independent regulator.
  2. Resources allocated to member states for allocation to operators and service providers within a national context are termed indirect assignment to differentiate from the directly assigned resources.
  3. The three resources are telephone numbers (as specified in Recommendation ITU-T E.164.1), international mobile subscription identifier (IMSI) (as specified in Recommendation E.212), and issuer identifier number (IIN) (as specified in Recommendation ITU-T E.118).
Last updated on: 19.01.2022
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