ENUM Advantages and Disadvantages VoIP World Congress 2006 Vienna, November 14th, 2006

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ENUMAdvantages and DisadvantagesVoIPWorld
Congress 2006Vienna, November 14th, 2006

• Richard Stastny, ÖFEG

The opinions expressed here may or may not be
that of my company
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Is ENUM Going a Full Circle?
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ENUM is defined by the IETF

• Electronic or E.164 NUMber mapping is defined by
  the Internet Engineering Task Force (IETF) in
  RFC3761 as
• the mapping of Telephone Numbers to Uniform
  Resource Identifiers (URIs) using the Domain Name
  System (DNS) in the domain e164.arpa
• URIs are used to identify resources on the
  Internet (e.g. http//enum.nic.at )
• The purpose of ENUM is to enable the convergence
  between the PSTN and the Internet

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ENUM in a nutshell
43 720 203 211

• take an E.164 phone number

• turn it into a FQDN

1.1.2.3.0.2.0.2.7.3.4.e164.arpa.

• query the DNS (for NAPTR)

• returns list of URIs

siprichard_at_iphone.at
mailtorichard.stastny_at_oefeg.at
sms tel[phone]
IN NAPTR 100 100 "u" E2Usip !.!SIPrichard_at_i
phone.at! .
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The basic idea of ENUM (RFC3671)

• The basic idea of ENUM was
• to allow end-users
• to opt-in with their EXISTING phone-numbers on
  the PSTN
• into e164.arpa
• to provide OTHER end-users with the capability
• to look up contact URIs on the Internet the above
  end-user wants to link to this number
• This kind of ENUM is called User ENUM

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ENUM Implementations
Delegations in e164.arpa as of Oct 24th, 2006

• 30 Greece
• 31 Netherlands
• 33 France Trial closed
• 350 Gibraltar
• 353 Ireland Trial
• 354 Iceland
• 358 Finland
• 359 Bulgaria
• 36 Hungary
• 374 Armenia
• 386 Slovenia requested
• 39 Italy
• 40 Romania
• 41 Switzerland Trial
• 420 Czech Republic Trial
• 421 Slovakia Trial
• 423 Liechtenstein Trial
• 43 Austria
• 44 UK Trial

• 246 Diego Garcia
• 247 Ascension
• 262 Reunion (fr)
• 290 Saint Helena
• 508 St. Pierre and Miquelon (fr)
• 52 Mexico requested
• 55 Brazil
• 590 Guadeloupe (fr)
• 594 French Guiana
• 596 Martinique
• 61 Australia Trial
• 62 Indonesia requested
• 63 Philippines Trial
• 66 Thailand
• 65 Singapore Trial
• 81 Japan Trial
• 82 Korea Trial
• 84 Vietnam
• 86 China Trial

• 1 North America (US, CA, Jamaika)
• additional Asian countries (Taiwan) have trials,
  but not in .arpa

http//www.ripe.net/enum/request-archives/
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The draw-backs of the original approach

• Privacy concerns reduced the usability of ENUM
  basically to VoIP
• Most VoIP providers do not provide end-users with
  SIP URIs to be reached on the Internet without
  termination fees
• Why should an end-user pay for the benefit of
  other users?
• How to overcome Metcalfes Law?
• Nobody understands ENUM

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But the real problem is

• User ENUM requires
• country opt-in
• end-user opt-in
• Service providers have no say in User ENUM
• So Service Providers using IP-based technology
  need other solutions to be able to Interconnect
• via IP-based technology and
• using E.164 Numbers

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NGN/IP Interconnect (VoIP Peering)

• If we take the All-IP paradigm seriously, we have
  two basic requirements
• Any real-time communication originating on IP and
  terminating on IP MUST stay on IP end-to-end
• This implies, it MUST NOT use the PSTN/ISDN to
  interconnect.
• Benefits are
• improved end-to-end functionality (BB codecs, IM,
  video, conferencing, presence, )
• Improved end-to-end QoS
• No additional cost beside of IP-access
• convergence possible at the end-users device

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Infrastructure ENUM first try

• A tree for service providers is needed
• ETSI created TR 102 055 ENUM Scenarios for User
  and Infrastructure ENUM discussing the options
  and the problems
• It should be a single global tree
• Service provider opt-in
• No regulatory involvement required
• But
• Who is in charge?
• Where to place the tree (public, private)
• How to get ALL service providers to agree on this
• etc., etc.

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Nevertheless, a solution was needed

• IP-based service providers wanted to peer
  (interconnect) their SIP traffic
• based on E.164 numbers
• So a number of VoIP peering federations including
  some kind of E.164 resolution where established
• XConnect, VPF, e164.info, SPIDER,
• Most of them based on ENUM technology

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The ENUM Matrjoschkas
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Private ENUMs

• Also called
• Operator ENUM
• Enterprise ENUM
• Carrier ENUM
• This is currently how service providers
  interconnect
• Variants
• Private ENUM in a walled garden extranet (GSMA)
• SIP Exchange with restricted access on the
  Internet (Cable providers, XConnect, SIP-IX, )
• public tree not in e164.arpa (e164.info)
• Advantages
• No user opt-in, NO REGULATORS INVOLVED,
  intrinsic peering agreements, savings in CAPEX,
  OPEX, MM-services
• Disadvantages
• limited reach,
• no global solution,
• how to peer with other federations?

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Infrastructure ENUM second try

• All types of private ENUMs have serious
  disadvantages
• limited reach,
• no global solution,
• how to peer with other federations?
• Only numbers from providers participating in the
  given federation can be reached
• To enable global reachability on IP, a single,
  common and global tree is required.
• The first goal of Infrastructure ENUM is to
  create an anchor place where any E.164 number can
  be found and will
• either be mapped directly to an ingress point of
  the destination network,
• or at least hints can be found in which private
  E.164 resolution spaces the number can be
  resolved.

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Public Infrastructure ENUM

• If Infrastructure ENUM is intended to allow the
  mapping of any E.164 number
• that can be reached via IP
• even if it terminates on the PSTN
• to a SIP URI,
• Infrastructure ENUM must be in the public DNS.
• But this is useless, if the resulting SIP URI
  cannot be reached
• So for Infrastructure ENUM also a global IP
  Interconnect (VoIP Peering) regime is required.
• ENUM is an applet to VoIP Peering

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Standardisation in IETF

• Two recent major developments in IETF regarding
  (VoIP) Interconnect
• ENUM WG extended scope to include Infrastructure
  ENUM
• Voipeer BoFs to create new SPEERMINT WG
• Session PEERing for Multimedia INTerconnect
• WG established 8. February 2006

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Separation of Scope

• The ENUM WG is primarily concerned with the
  acquisition of Call Routing Data (CRD) e.g. a SIP
  URI,
• while the SPEERMINT WG is focused on the use of
  such CRD.
• Importantly, the CRD can be derived from ENUM
  (i.e., an E.164 DNS entry), or via any other
  mechanism available to the user.

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Scope ENUM and SPEERMINT
Infrastructure ENUM
ENUM Lookup
I-ENUM
Policy Database
Policy Lookup
SPEERMINT
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Current I-Ds in ENUM

• Infrastructure ENUM Requirements
• The E.164 to Uniform Resource Identifiers (URI)
  Dynamic Delegation Discovery System (DDDS)
  Application for Infrastructure ENUM
• Combined User and Carrier ENUM in the e164.arpa
  tree (interim solution)
• The ENUM Branch Location Record (interim
  solution)
• IANA Registration for an Enumservice to Hint to
  E.164 Resolution Namespaces (ERN)

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SPEERMINT Interconnect

• Interconnection procedures
• (Eventually take output of ENUM)
• Analysis of target URI
• Check routing and peering policy (e.g. federation
  and NNI detection)
• Discovery of next hop
• Routing of SIP messages
• Session establishment
• Media transfer

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Types of Peering

• Direct peering
• the originating provider may identify and
  interconnect directly with the terminating
  provider
• Assisted peering
• involves the deployment of centralized SIP
  elements on the Internet or by a federation
• Indirect peering
• involves transit SIP elements for the routing of
  SIP messages and eventually also for media

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Finding the Policies

• Location
• of the terminating provider
• Interoperability
• compatibility with terminating provider
  (identifying the NNI/UNI)
• Security
• of message transport (TLS, IPSec, VPN, ..)
• Trust
• authentication, privacy, identity, SPIT
  prevention,
• Routing
• of messages to next hop
• Cost
• Fees, type of charges,

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What are the Benefits of ENUM?

• ENUM is using the DNS
• its there, it works, its global, it scales,
  its reliable, its open, anyone can use it
• saving CAPEX
• Enables the originating administrative domain to
  do an All Call Query (ACQ) to find the
  destination network
• Ultimate solution in Number Portability
• Provisioning is done only by the destination
  (recipient) administrative domain for the E.164
  numbers this domain is hosting
• saving OPEX
• Enables all multimedia (MM) services for E.164
  numbers for all sessions on IP end-to-end
• enables convergence (whatever that means)

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What are the benefits of SPEERMINT?

• Enable interconnection in public and private
  environments
• Use the DNS also for policy functions
• saving CAPEX
• Provisioning done mainly by the destination
  administrative domain
• saving OPEX
• Enables multimedia (MM) services for any Public
  User Identifier for all sessions on IP end-to-end

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Benefits in a nutshell

• The major benefits of Infrastructure ENUM and
  SPEERMINT for (VoIP) carriers and (VoIP) service
  providers is to save costs
• Minimal CAPEX for setting up the required
  infrastructure to provide the routing data
• Minimal OPEX for maintaining routing data
• Announce the E.164 numbers you host (in ENUM)
• Announce the domains you host (in DNS)
• (make bilateral or multilateral peering
  agreements)
• Query ENUM and DNS to find any other destination
  provider

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What are the Open Issues?

• The Internet is based on end-to-end communication
  and best effort, no central intelligence
• this causes also a lot of problems (SPAM, DoS,
  spoofing, phishing, )
• The PSTN has central control, QoS and a different
  business model,
• but it is a one trick pony
• The dream of the NGN
• take the benefits of the PSTN (especially the
  business model) and move it over to IP technology

The answer is money, what was the question?
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Currently we have some options

• NGN, IMS?
• trying to rebuild the IN-silos on IP
• keeping the central intelligence by adding
  service control
• problems contrary to the Internet Architecture
• getting to complex
• loosing the innovation potential
• Internet and P2P SIP?
• Back to Keep it Simple, no administrative
  overhead, end-user control
• or The Balkanization of the Internet?

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What about User ENUM?

• User ENUM may finally co-exist with
  Infrastructure ENUM
• Infrastructure ENUM will basically be used as a
  SS7 replacement for SIP- based services
• User ENUM is an end-to-end Internet service
  usable for any kind of end user communication
• End user will never host all their services with
  one provider
• It may be used as an overlay for any type of
  services communities and enterprises.

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From the IETF67 last week in San Diego

• Infrastructure ENUM
• I-Ds in WGLC
• No decision on ENUM root domain by IETF
• RFCs will be forwarded to ITU-T
• The ITU-T has to decide on the root
• Void draft revived
• name changed to UNUSED for unallocated and
  unassigned numbers
• URI changed to data

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• Thank you

Richard Stastny ÖFEG 43 664 420
4100 richard.stastny_at_oefeg.at http//voipandenum.b
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