1. IP-Enabling The Global Telephone Directory
ENUM
IP-Enabling The Global Telephone Directory
Miami, Florida
February 12, 2004
Session SP-10
Rom Mattesich, CEO
Stratum1, Inc.

2. E.164 … A Major Accomplishment of the 20th Century
Over a billion people can be reached with a single telephone number.
E.164 Numbering plan is the “glue” that made complex network connections happen
…with one of the simplest user interfaces ever, the 12 digits DTMF pad!
… comprehensible in every language known to civilization.
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R. Mattesich

3. E.164 … Chocking On Its Own Success
Tracking a Go-Getter by his business card:
Company____________________
Name_______________________
Title________________________
Address_____________________
Reach Info:
Main. Tel No:______ _________
Direct Tel No:______ SMS Screen Name:___
Toll Free No:_______ DID for Callback___
Voice Mail:_________ Company URL:____
Fax No:____________ Personal URL:_____
Cellular No1:____________
Cellular No2:____________
Pager No:______________
Home No:______________
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R. Mattesich

4. E.164… Chocking on its Own Success(II)
Numbers are a scarce resource
They are being depleted much faster than population growth
Cellular subs/family unit require more numbers/family
Number portability escalates consumption of tel. numbers
Number of new area codes is multiplying
Cost and inconvenience of cutover to new codes are very burdensome to the public.
More E.164 digits are almost inevitable! (Four more are possible in the NANP)
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R. Mattesich

5. Goals
Customer should not consume more than one fully qualified E.164 address for each of the many forms of access and services which he/she needs to survive/prosper in the age of convergence and mobility
Customers should screen form/time/priority of access at their convenience
VoIP will be truly ubiquitous by making the PSTN/Internet transition seamless and transparent to subscribers
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R. Mattesich

6. ENUM – The Promising Solution
The IETF’s ENUM protocol offers the best opportunity for full integration of PSTN and IP Networks by mapping E.164 numbers into fully qualified DNS numbers.
The full functionality of the Internet becomes accessible through the simplest device ever, the POTS phone!
Communication phone to phone, phone to computer, and/or IP-enabled phones becomes seamless and transparent to users.
“Enhanced values” services like Unified Messaging will finally have a chance to blossom
Wireless based Internet access much friendlier w/ENUM
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R. Mattesich

7. A Brief Review- The E.164 NUMBERING PLAN
E.164 is the international public telecommunication numbering plan administered by the ITU. It defines number structure and functionality for four principal categories of numbers: Geographic Areas, Global Services, Networks, and Groups of Countries.
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8. Number structure for geographic area
E.164 Structure
Number structure for geographic area
Int’l
Access
Code
(+)
Country
Specific
In US:
011
Country Code/WZ
National
Destination
Code (ndc)
cc=1-3 digits(1st=WZ)
ndc maximum 15-cc-ndc digits
National Significant Number (NSN)
International public telecommunication number for geographic areas (maximum 15 digits)
Subscriber Number +
USA
Example 1
Example of a fully qualified E.164 Number
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R. Mattesich

9. World Zones - geographic areas
E.164 Structure
World Zones - geographic areas
(1st CC Digit)
1… USA and North America
2… Africa
3… Europe
4… Europe
5… Central and South America
6… Asia
7… Russia
8… Special Services (Inmarsat, FreePhone)
9… Middle East
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R. Mattesich

10. ENUM – Captures The Power of DNS for Dynamic Addressing
What is ENUM?
Enum is the name used by the world telephone numbering working group of the IETF to describe a unique method of using the Internet DNS to map E.164 numbers to URL’s.
E.164 Number
Map Into
Uniform Resource
Location (URL)
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R. Mattesich

11. A New Home for ENUM on the Internet… Top Level Domain Names
Label
Description
com
Commercial organizations
edu
Educational institutions
gov
Government institutions
mil
Military groups
net
Network support centers
org
Nonprofit organizations
arpa
Internet infrastructure (home for ENUM)
int
International organizations
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12. An Example of ENUM Mapping
Dialed Number’s undergoes following conversions:
From “Fully Qualified E.164 Number”
To “Strip all non digit symbols”
To “Reverse string, most important
digits read from left to right.
Same priority as in URL’s”
To e164.arpa “Fully qualified URL”
The “.” between the digits, create nodes in the DNS hierarchy
Responsibility for DNS Admin can now be delegated to successive layer of authority and multiple operators comparable to systems in place for E.164 Admin.
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13. ENUM- Search Algorithm
.root
404 Error
Internet Resource Not Found
Alternate route to PSTN!
Top Level Domain Names
.arpa
.com
.uk
.int
.e164
4.4. (uk)
.co
.itu
1.nanp
3.3. (fr)
(“ARPA” as a TLD is a subject of some international controversy)
for
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R. Mattesich

14. ENUM Builds Upon the Power of DNS
A FQDN Query to DNS produces an “A” record, which returns an IP Address, e.g.,
An ENUM call to DNS ( e164.arpa), allows Yvonne to advertise a number of services. Examples:
$ORIGIN e164.arpa “Yvonne’s the owner”
IN NAPTR “u” “sip+E2U” “Phone me via SIP”
IN NAPTR “u” “mailto+E2U” “or me”
IN NAPTR “u” “http+E2U” “!^.*$! “look me up in my personal web site”
IN NAPTR “u” “tel+E2U” “!^.*$!tel: !” “Try me on the cellular”
URI
Control Characters
Above services are all available from a single number
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R. Mattesich

15. Dialing an IP-Enabled Phone... The ENUM Way
DNS Servers
4. DNS Server returns NAPTR
sip:
6.DNS responds w/A Record
3. Sip gateway queries
e164.arpa
5.Gateway selectsNAPTR
Yvonne
PSTN
IP Network
Xavier IP
SIP Server for
Sip Gateway
2. PSTN maps and routes
Yvonne’s E.164 number to
near-end gateway.
IP Phone
7..Gateway completes call
To SIP port on server
1. Xavier single stage
dials Yvonne at
Above communication is seamless and transparent to both X & Y
SIP Gateways dips into DNS twice:
(1) Get List of Yvonne’s Services
(2) Selected service is sent back to DNS to get destination IP (A Record)
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R. Mattesich

16. ENUM – The Promise and The Bane
ENUM essentially maps a multiplicity of services to a single telephone number
Creation/Provision of these services is an edge function… not embedded in the network, such us with IN/SS7/SCP.
The transformation is profound: value added services such as call forwarding, number translation, conference calling, and many more, will be created by enterprises and consumers, not telephone companies!
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17. Who Owns The Numbers?
ENUM’s records point to traditional telephony as well as to all sorts of Internet services.
Telephony, as well as ISP’s, may claim rights to blocks of numbers.
Consumers may want to demand different services (under the same ENUM) from different providers.
One ENUM can point to multiple providers.
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18. Conceptual ENUM Admin Hierarchy
Goal:
Promote Competition w/o Chaos.
Tight administrative coupling is necessary between E.164 and ENUM Registries
Most Likely
Assignee: E164Country Registrar (NeuStar in the USA)
Fully
Competitive
Level
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19. ENUM Raises Important, Unresolved Social Issues
Privacy: Democratic countries (US in particular) shun One Number ID.
A popular Internet command (WHOIS) reveals much contact info about registrant
ENUM Info needs some protection from third parties
Consequences of spammers/pornographers getting hold of ENUM data can be devastating to users
See ENUM – A Case Study in Social Irresponsibility
These issues are still being debated, but value of ENUM is so compelling that most problems are likely to be resolved soon.
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R. Mattesich

20. ENUM… A Knowledge Base on The Internet
Check up some useful document/web sites to get more info:
RFC 2915:
RFC 2916:
ENUM working group charter:
SIP working group charter:
Web site for IANA:
Web site for ICANN:
International Telecommunications Union (ITU):
Search for E.164
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21. Who Is Behind ENUM? IAB US EU France Sweden Switzerland Austria Korea
Companies Standard Bodies Countries US EU
France
Sweden
Switzerland
Austria
Korea
Australia
NeuStar
Verisign
AT&T
Telcordia
Cisco
IAB
IETF
ITU
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22. Implementations of ENUM and ENUM-like systems: US
NeuStar’s Public Trial (
Verisign’s WebNum (
Netnumbers (
ENUMNic (
ENUMWorld (
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23. Implementations of ENUM: Other Countries
France: Numerobis
Austria: Austria ENUM Site
Korea: KRNIC
Sweden: Post and Telestvrelsen
Switzerland: Swiss Federal Office of Communications (OFCOM)
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24. Some Key Terms Related to ENUM
DNS Domain Name System
NS Name Server (for a domain)
NAPTR Naming Authority Pointer
URI Uniform Resource Identifier
URL Uniform Resource Locator
E2U E.164 to URI conversion
$ORIGIN followed by originating domain name
SIP Session Initiation Protocol (similar to HTTP) popular for VoIP
PSTN Public Switched Telephony Network
IETF – Internet Engineering Task Force is an international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet.
Any questions?
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R. Mattesich