VoIP and ENUM Short Introduction

1
VoIP and ENUM Short Introduction

• AK-TK Workshop
• ÖFEG, March 11th , 2004
• Richard STASTNY
• ÖFEG, Postbox 147, 1103-Vienna
• tel[phone]mailtorichard.stastny_at_oefeg.
  atrichard_at_stastny.com

2
Content

• Some basic definitions
• The pieces
• Naming and addressing on the Internet, URIs
• The Domain Name System (DNS)
• VoIP and SIP
• DDDS and ENUM
• Putting all pieces together
• ENUM History
• Administration of ENUM

3
What is required to establish a communication?

• (User) Identification (and authentication)
• identification of the user to the service
  provider (registration)
• userID/PW, IMSI,
• always provider specific, not portable
• Address
• current network access point of the user terminal
  device
• e.g. IP address,
• network specific, not portable
• Name
• mapped (dynamically) to the current address of
  the terminal, where the user has registered
  himself
• mostly service related, sometimes portable
• Terminology not consistent
• e-mail address, address-of-record are names

4
What is a phone number?

• always numeric (with some exceptions)
• used as identifiers, addresses and names
• started as addresses and identifiers
• now with number portability and service numbers
  also used as names
• Types of phone numbers
• private, local, national, international
• E.164 numbers or International Public Telephone
  Numbers
• Structure of E.164 numbering plan
• CC N(S)N e.g. CC NDC SN
• max 15 digits including 1-3 digit CC
• no prefixes or access codes -gt part of dialing
  plans

5
Naming and addressing on the Internet

• Addresses IPv4 and IPv6
• Names Uniform Resource Identifier (URIs)
• alphanumeric character strings that identify
  abstract or physical resources on the Internet
  (RFC2396)
• different formats, need to be defined in an RFC
  and registered with IANA
• Examples
• http//www.enum.nic.at
• http//80.121.237.198
• mailtorichard.stastny_at_oefeg.at
• siprichard_at_iphone.at
• tel[phone]
• URI's may contain IP addresses or domain names
• Domain names need to be resolved with the Domain
  Name System (DNS)

6
Domain Name System (DNS)

• The DNS is a distributed lookup system arranged
  hierarchically
• It consists of 4 components
• the name space
• the name servers making that name space available
• the resolvers (clients) querying that name space
• a protocol
• Domains, zones and delegation
• a domain is a set of host names consisting of a
  single domain and all the domain names below it
• a zone is any domain name delegated by an
  ancestor zone, ie a point of delegation
• it contains all descendant domain names not been
  delegated
• delegation means that somebody else is
  responsible for the subdomain
• Resource Record (RR) is a unit of data
• it defines some attribute for the domain
• eg. an IP address, a mail route, a VoIP signaling
  route, a delegation
• What the DNS is doing I have "x", give me "y"

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Name Space und Name Server
point of delegation
root
Top Level Domains
com
de
at
se
uk
org
info biz
net
int gov mil edu
gTLDs
ccTLDs
Label
Second Level Domains
stastny
microsoft
co
oefeg
xxx.stastny.com
oefeg
atc
yyy_at_stastny.com
oefeg.co.at.
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SIP Trapezoid
Location Server
DNS Server
REGISTERjiri_at_195.37.78.173.
DNS QUERY SRV iptel.org
DNS
details next slide
SIP
Inbound Proxy Server
Outbound Proxy Server
INVITEjiri_at_iptel.org
SIP
SIP
jiri_at_iptel.org
SIP
caller_at_sip.com
Media (RTP)
User Agent A
User Agent B
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Basic SIP Call-Flow (Proxy Mode)
Location Database
Proxy
sipjiri_at_195.37.78.173
Caller_at_sip.com
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ENUM and DDDS

• The Dynamic Delegation Discovery System (DDDS) is
  a generic system to implement a binding of
  strings to data stored in a database and is
  defined in RFCs 3401-3405
• The generic algorithm is defined in RFC3402
• RFC3403 defines the usage of DNS as database and
  therefore also defines the DNS Resource Record to
  be used
• Naming Authority Pointer or NAPTR
• it also defines the fields of a NAPTR and how to
  process a NAPTR
• ENUM is a DDDS application
• RFC2916bis defines therefore
• the algorithm how to map a E.164 number to a
  domain name
• the service_field "E2U" 1(servicespec)
• how to register servicespecs with IANA (template)

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ENUM in a nutshell

• take phone number

43 1 979 33 21

• turn it into a FQDN

1.2.3.3.9.7.9.1.3.4.e164.arpa.

• ask the DNS for NAPTR

mailtorichard_at_stastny.com

• returns list of URIs

siprichard_at_iphone.at
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How does ENUM work ?
Telephone Number (TN) 43 1 979 33 21 translates
to
1.2.3.3.9.7.9.1.3.4.e164.arpa
Tier 1 resolution to NS of authority ( pointer
only)
1.2.3.3.9.7.9.1.3.4.e164.arpa. IN NS ns1.iphone.at
Tier 2 resolution to NAPTR record and SIP URL
controlled at the end office
IN NAPTR 10 10 "u" E2Usip !.!SIPrichard_at_ip
hone.at! .
set up call
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So what is ENUM adding?
ENUM DNS
IN NAPTR 3.4.3.9.1.1.1.3.9.3.0.1.8.7.8.e164.arpa.
?
... NAPTR ... "!.!sip19343_at_fwd.pulver.com!"
DNS SRV lookup fwd.pulver.com
SIP
SIP
server
server
878103931119343
sip19343_at_fwd.pulver.com
session
sipaxelm_at_nic.at43.at
sipmah_at_nic.at43.at
sip18341_at_fwd.pulver.com
sip19343_at_fwd.pulver.com
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Bridging Internet PSTN with ENUM
Internetz
PSTN
sipmah_at_nic.at 43 59966 366001
43 664 4213465
Media Gateway
ENUM DNS
31 20 535 4412
sipaxelm_at_nic.at 43 59966 366003
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Options for Corporate Users
32_at_iphone.at
32
43780 179780 32
43179780
43179780 32
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So how can ENUM be used?

• Business with IP PBX or IP Centrex
• with geographic and/or numbers for networks
  (opt-in)
• linking IP islands together globally via the
  Internet
• Residential with my geographic number (opt-in)
• either as secondary line or as primary line
  (ported out)
• Residential with my mobile number
• terminate IP originated calls on IP, plus
  evenually forwarding or forking to my mobile
• operators may provide forced ENUM access from the
  PSTN
• Residential and Business ENUM-only number
• IP device can be reached from PSTN and IP
• calls may be dumped to IP in the originating
  network

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ENUM and VoIP as a Trigger

• ENUM is tightly linked with numbering and
  therefore with the regulatory framework
• Deployment of ENUM is also tightly linked with
  the deployment of VoIP
• Deployment of VoIP causes a direct conflict
  between Telco's and ISP's
• Deployment of ENUM involves NRA's and Registries
  (in Europe primarily the ccTLD's)
• ENUM and VoIP therefore cause a lot of questions
  and issues to surface.

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A (very short) ENUM History

• Sept. 2000 IETF ENUM WG RFC2916
• 2001 Various Workshops (ITU-T, Europe, US, )
• 2002 ITU-T Interim Procedures (IAB, RIPE-NCC)
  ETSI SPAN11 TS "ENUM Administration in
  Europe" Austrian ENUM Trial in
  operation (Sept. 2002)
• 2003 ETSI SPAN11 TS "Minimum Requirements for
  Interoperability of European ENUM
  Trials" IETF RFC2916bis WGLC
  Various national and international ENUM Trials
  using different scenarios and numbering
  resources and using different
  ENUM-enabled products
• 2004 ETSI ENUM Plugtests and Workshop
  ENUM ready for production

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Name Space .arpa
root
com
org
info
net
de
int gov mil edu
at
se
uk
gTLDs
ccTLDs
Tier 0
co
oefeg
stastny
microsoft
Tier 1
xxx.stastny.com
oefeg
atc
yyy_at_stastny.com
oefeg.co.at
Tier 2
0.8.7.9.7.1.3.4.e164.arpa
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The ENUM "Tiers"
Registry
Tier-0
International-RIPE-NCC and ITU-TSB
National
CC 43
CC 1
Directs the DNS query to the customers Tier-2
providers. An NS record is provided for each
subscribers telephone number
Registry
Registry
Tier-1
Tier-1
Stores a list of service specific internet
addresses in the form of URIs in a DNS resource
record called NAPTR for each subscriber. Returns
the full list of Internet addresses associated
with the E.164 number being queried.
Provider
Tier-2
An NS record is an authoritative Name Server DNS
record used to delegate to subordinates
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ENUM Delegations
Delegations in e164.arpa as of 11. March 2003

• 31 Netherlands
• 33 France
• 358 Finland
• 36 Hungary
• 374 Armenia
• 40 Romania
• 41 Switzerland
• 420 Czech Republic
• 421 Slovakia
• 423 Liechtenstein
• 43 Austria
• 44 UK
• 46 Sweden
• 48 Poland
• 49 Germany

• 55 Brazil
• 86 China
• 246 Diego Garcia
• 247 Ascension
• 290 Saint Helena
• 971 UAE
• 88234 Antarctica Mobile
• 87810 VISIONng UPT

additional Asian countries (Korea, Japan, ) soon
to come
http//www.ripe.net/enum/request-archives/
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The End
Thank you for your attention
Contact (not Content) is King
Douglas Rushkoff