Is “E164.arpa” The Only
Tier-1 ENUM Registry Services?
Douglas Ranalli, Founder
Bias: As the Founder and Chief Strategy Officer of NetNumber.com, a
provider of commercial ENUM services under the “e164.com” domain, I
believe in the value of competition in ENUM services at both the Tier-1
(Registry) and Tier-2 (NAPTR services) levels.
Given this underlying belief, I support the efforts of the
International Telecommunication Union (ITU) in defining a public ENUM
Registry under the “e164.arpa” domain as a viable competitive option
for the delivery of global ENUM services.
Furthermore, NetNumber plans to participate actively in winning
contracts at the ITU Member State level to provide Registry services under
the public ENUM structure. However,
while I support “e164.arpa” as one viable competitive option, I do not
believe that the industry is best served by viewing a public ENUM
implementation as the exclusive Tier-1 Registry option.
This paper addresses three key questions relating to the
deployment of global ENUM services:
the IP-communications industry best served by utilizing “e164.arpa” as
the exclusive ENUM Registry implementation?
is the competitive alternative?
the competitive model meet the unique operational demands of the emerging
the emerging IP-Communications industry best served by utilizing
“e164.arpa” as the exclusive Tier-1 ENUM Registry implementation?
public ENUM registry implementation is based on asking 200+ ITU Member
States to each define a structure for operating ENUM Registry services for
the subset of E.164 numbers that fall under their control at the country
code level. For example,
France will define a structure for the registration of E.164 numbers under
country code 33, Germany under country code 49, and so on.
A perceived strength of the “e164.arpa” model is that it
derives authority from the existing PSTN regulatory model.
By comparison, a potential weakness of the model is the widely
distributed nature of the solution.
E164.arpa will be slow to develop. It
is simply time consuming and difficult to coordinate the selection of
Tier-1 ENUM service providers across 200+ ITU Member States.
Pricing policies, billing policies, payment terms, etc. are likely to vary
from Member State to Member State. Complexity
never comes for free. In an
environment without a competitive alternative, will “e164.arpa”
achieve a pricing model that reflects the needs of the emerging industry?
Restricting ENUM to one public Tier-1 implementation imposes an artificial
limit on the creative process. In
a competitive market the focus of Tier-1 service providers will be to
“develop services that drive the utilization of ENUM services”.
In an exclusive public implementation a major driving force
becomes: “win contracts for providing services under e164.arpa".
Given the fact that the market has little practical experience with
ENUM to date, are we prepared to artificially limit investment and
creativity at this early stage in the process?
The 200+ Tier-1 service providers under “e164.arpa” may never achieve
consistent policies regarding registration procedures, conflict
resolution, disclosure of registrant information, etc.
Given the potential for policy inconsistency, what impact will this
have on early adopters of ENUM services?
How will a multi-national corporation with 10,000 employees located
in 47 offices across 22 countries register for global ENUM services under
the exclusive e164.arpa model? Will
it be practical to register for global ENUM services under the
“e164.arpa” model in the near term or even medium term?
How long are we willing to wait?
the concerns raised above, are we absolutely certain that limiting ENUM
Registry services to a single public implementation under “e164.arpa”
is in the best interests of the emerging IP-Communications industry?
is the competition based alternative model?
Introducing competition to Tier-1 ENUM services has the
potential to address many of the risks associated with an exclusive public
ENUM model as described above. Outlined
below is one view of how a competitive ENUM Registry model might develop:
Private/Enterprise ENUM Services:
Large enterprise customers may find value in deploying private ENUM
services to provide closed user group functionality, in addition to
participating in a public ENUM service.
As such, the communications systems deployed within these closed
user group environments will be required to query more than one Tier-1
ENUM service. Example:
"e164.company.com” for private user group information and
“e.164.arpa” or "e164.com" for external/shared information.
Commercial ENUM Services:
Example: “e164.com”: NetNumber
has deployed a commercial ENUM service under "e164.com" and we
are currently working with a large number of IP-communications vendors to
incorporate NetNumber’s ENUM services into their applications.
As part of ENUM integration process, NetNumber provides an ENUM
resolver that can be configured to simultaneously query several customer
defined ENUM services and return prioritized results.
Public ENUM Service:
“e164.arpa”: The efforts to advance a public ENUM implementation under
“e164.arpa” are well documented and require no further explanation.
the competitive model meet the unique operational demands of the
below is an analysis of several issues that have been raised by industry
participants over the past few months regarding the introduction of
competition in Tier-1 Registry services:
Too many competitive ENUM services will make queries
ineffective: The concern has been raised that a competitive market place
will produce hundreds or even thousands of ENUM services that might all
need to be queried by a communications application to obtain complete
information. I see three
reasons why a more likely outcome will be a limited number of Tier-1 ENUM
To date, there is no evidence of the market deployment of hundreds
or thousands of ENUM services. There is however evidence of an effort to create one public
implementation and a limited number of commercial implementations.
Underlying Economics Of Directory
The natural economies of scale in providing DNS Registry services
tend to favor a limited number of Registry providers, not a widely
Underlying Customer Behavior:
Customer's aren't likely to be interested in configuring their
communications platforms to query a large number of Tier-1 ENUM services.
This natural desire for simplicity will stimulate the market to
achieve balance with a limited number of competitive providers.
Query Delay From Searching Multiple ENUM Services:
The issue has been raised that too much delay might be introduced by
sequentially querying multiple ENUM services to obtain accurate addressing
information. Under a model of
a limited number of viable ENUM services, I propose that a more likely
outcome is that ENUM resolvers will be designed to simultaneously query a
set of ENUM services defined by the customer.
NetNumber's publicly available ENUM resolver has already been
deployed with this flexibility.
Cost and Complexity With Users Registering In Multiple ENUM
services: The issue has been raised that a competitive market might
cause E.164 Subscribers to feel compelled to register their E164 names in
multiple ENUM services. Or
similarly, we might end up with confusion over conflicting registrations
in different services. Both
of these concerns would be true if a Subscriber felt a need to “protect
their numbers” against unauthorized registrations in alternate ENUM
Registries. NetNumber has
always approached the industry with the vision that registration
validation is a requirement for an ENUM service provider.
In a world where Subscriber rights are protected, no incentive
exists to register with more than one ENUM service.
Subscribers and Service Providers will select the ENUM service that
best meets their needs and register accordingly.
The assumption I'm making is that a validation structure can be
defined for or by the ENUM industry to protect the rights of Subscribers.
Clarification of the role that government regulatory agencies might
be willing to play in defining acceptable ENUM validation mechanisms
represents a topic for further discussion.
While I support “e164.arpa” as one viable competitive
option for the delivery of global ENUM Registry services, I do not believe
that the Internet-Telephony industry is best served by viewing a single
public ENUM implementation as the exclusive Registry option. Given agreement on an ENUM registration validation structure,
competition can play an important role in advancing the use of the newly
defined ENUM standard.