Ofcom wants to restore trust in phone numbers through a common numbering base

Ofcom wants to restore trust in phone numbers through a common numbering base

On April 11, 2019, Britain’s telecoms regulator Ofcom has published three public consultations, open until June 6, on the future of telephony in the United Kingdom, in order to:

We will return to numbering and interconnection in future posts and we will focus today on trust in phone numbers.

Ofcom proposes a common base of phone numbers

Ofcom’s central proposal is to create a common base of numbers to ensure that a number presented by the caller to the called party is authentic. The purpose of Ofcom is to reduce the number of nuisance calls or fraudulent calls. Ofcom’s belief is that a common base of numbers is the best way to achieve this. Ofcom’s goal is for the base to come into service in 2022, by which time the majority of calls between landline numbers should be in voice over IP. This base would also support more efficient protocols for number portability and a more efficient routing of ported numbers. Ofcom believes that it is up to the industry to implement such a base.

A country without a common system for managing number portability, where voice over IP and IP interconnection are little developed

Unlike most continental European countries and the United States, the United Kingdom has still not implemented direct routing to the operator using calls to ported numbers. Similarly, Ofcom’s latest analysis of voice markets in 2017 maintains TDM as the benchmark technology for BT’s interconnection. Finally, any user of a copper pair of BT, even if he is a customer of a unbundling operator for his access to the Internet, buys his fixed telephony from BT, through a WLR (wholesale line rental) contract subscribed by his internet service provider.

However, in most countries, the delivery of interconnection traffic according to the relevant technology, which involves the routing of national calls number by number and not by block of 10 000 numbers, relies on the routing system, also number by number, of calls to ported numbers.

If it were possible to route calls to ported numbers through the operator to which the number block has been assigned, routing calls to Voice-over-IP numbers through the TDM switches that you are trying to decommission is not a solution. The direct routing of calls to the operator recipient of the ported number or to the IP switch on which the client has been migrated can be done without a common base of the numbers, but it is nevertheless much easier to set up such a data base when there are 285 fixed and 67 mobile operators whose call termination charge is regulated.

How to catch up with avant-garde measures

Ofcom could have insisted on imposing for 2022 that the Competitive Appeals Tribunal, on the complaint of the mobile operators for insufficient economic justification, had refused in 2008, namely a base for routing ported numbers on the one hand and numbers migrated to IP on the other hand.

Ofcom’s solution for a common numbering base, innovates functionally (through number authentication) as well as from a technical point of view (by considering a blockchain-secured decentralized register.) Noting the current incapacity of operators to verify whether the caller has the right to present such and such a number, Ofcom takes up the conclusions of the NICC, the British telecommunication standardization body, and advocates the creation of a database of all numbers (geographical, non-geographic and mobile) allocated to or ported to each operator.

Ultimately, this common database of numbers should be complemented by the implementation of the new IETF standard, STIR, Secure Telephone Identity Revisited. The base will show that a number can be legitimately presented by an operator. STIR, which will incorporate the consultation of security certificates attached to each number from each SIP trunk, will show end-to-end whether each number presented on each call is legitimate.

As for the implementation of the common number base, Ofcom is experimenting with blockchain technology. Between 285 fixed operators and 67 mobile operators, is this realistic? If there is only one file exchange per day between all the operators, this is likely. On the other hand, if the requirements for no service interruption in case of number porting or migration become stronger, and each port or migration of a number triggers a decentralised transaction under Blockchain, it is not certain that the Blockchain technology could support the required load.

Beyond restoring trust in the phone number, Ofcom notes in its conclusion that a common base of numbers is a necessity to offer new services. Will we thus revive an e-Num base?

A big gap in the public consultation: governance

Any constitution of a good which is common to all the operators of a country requires an extremely heavy work of the development of the governance of this common good. Here, the common good is the function, i.e. the direct routing of authenticated numbers. Whether the implementation is a classic centralized database or of a Blockchain-secured decentralized registry does not change the complexity of the governance issue: how are the governing bodies (general assembly, board of directors, bureau) constituted? What are the laws of association? Which rules of procedure are required for all? How are common expenses shared? So many questions for which the British telecom industry has no experience and for which the three years that separate us from 2022 will not be too much.

What lessons could ARCEP draw from it?

In 2018, by its decision n ° 18-0881, ARCEP took a step towards the authentication of the telephone number: “ARCEP recommends to the operators who propose offers allowing the customers to choose as caller ID or a different French number from the one he assigned to him for his telephone line:

  • to ensure, contractually and technically, that the use of the number chosen as caller ID or issuer identifier by an end user has been previously authorized by the assignor;
  • to be able, contractually and technically, to require the calling end-user at any time to always have the authorization of the number allocator to use as a caller ID or issuer;
  • to be able, contractually and technically, to suspend without delay the service allowing the modification of the caller ID or issuer identifier to end-users who do not respect the conditions of use and, where appropriate, to territoriality.

These recommendations pursue the objective of good use of numbers and consumer protection against possible abuse. “

ARCEP even adds: “In order for these rules to be applied effectively to protect consumers, it seems reasonable that measures should be implemented very quickly, or even in real time, by the operators on the networks in transit. call flows “.

But ARCEP does not go further. It does not require operators to centralize the numbers submitted by a third party in a database. It also does not require response time for these checks. But any administrative request receives an answer in several days, when the campaigns of prospection generate millions of attempts of call in a few hours. It would be desirable for ARCEP for take inspiration from Ofcom and ensure a real implementation of its very legitimate recommendations.