Enumservice VOID draftstastnyenumvoid00

1
Enumservice VOIDdraft-stastny-enum-void-00

• Richard StastnyLawrence Conroy
• IETF60 San Diego

2
Abstract

• Registers the 'ENUMservice' 'void' using the URI
  scheme 'mailto'
• This 'ENUMservice' SHALL be used to indicate that
  the E.164 number or E.164 number range connected
  to the domain used in DNS as described in RFC3761
  is not assigned to
• an end-user in case of an E.164 number or
• to a communication service provider in case of an
  E.164 number range.

3
Current Situation

• For ENUM, the E.164 number assignee has the
  exclusive right to register a domain associated
  with "their" number, and has exclusive control
  over the content made available in this zone.
• If an assignee of an E.164 number does not choose
  to register the associated ENUM domain, then any
  DNS query on that domain will return a response
  indicating 'no such domain' (NXDOMAIN, code 3).
• If no registration exists associated with an
  E.164 number, then that potential caller (or
  their agents) have no further information, and
  drop the call to their default network (e.g. the
  PSTN), assuming that this will route the call
  appropriately.

4
The problem

• Some NRAs now allocate number ranges for
  exclusive use of ENUM registrations (e.g. 43780
  in Austria).
• Calls to E.164 numbers in this range MUST be
  processed using ENUM, and delivered to the URI
  generated as a result of a successful ENUM query.
  
• Such a call CANNOT be simply "dropped" onto the
  default network for delivery.

5
The issue

• The originating user agent is unaware of this
  choice, may assume to drop the call to the PSTN
  and the call will fail.
• So a mechanism "between" a registration holding
  NAPTRs with URIs and the lack of a domain
  registration would be useful.
• As there is no end user as an assignee for an
  unused number, there cannot be a registration for
  the associated ENUM domain.
• It would be useful if the originating end user
  could receive a response that states "there is no
  service via this number.

6
The proposed solution

• We propose an explicit indication of this "number
  unassigned" state.
• This uses a NAPTR in the "enclosing" zone, with
  an enumservice called VOID that should be taken
  as an assertion that the associated E.164 number
  is not assigned to an end user for communications
  service it's an unused number.
• This NAPTR can also be used by an NRA to indicate
  number blocks that it has reserved or has not
  allocated, or has not assigned to a service
  provider.

7
The mailto URI

• Where a number (or number range) has not been
  assigned to an end user, there cannot be an
  associated ENUM registration.
• Thus there cannot be information made available
  via ISIS/Whois on the identity of the current
  "owner" of the number.
• For this reason, we propose that the VOID
  indication also includes an email address by
  which the authority responsible for this number
  (or range) can be contacted.
• This may not be the same entity as the one that
  maintains the DNS service for that "enclosing
  zone" often the NRA will sub-contract a Registry
  Operator to maintain the DNS, but it is the NRA
  who is the authority for the E.164 number range,
  not that Registry Operator.

8
Enumservice VOID

• Enumservice Name "void"
• Type(s) "void"
• Subtype(s) "mailto"
• URI Scheme(s) "mailto"
• Definition of expected action
• If a NAPTR with this ENUMservice is received, it
  indicates that the queried E.164 number is
  currently unassigned to an end user for
  communications service.
• The recipient SHOULD treat this response as if
  they had received a "number not in service"
  indication from a terminating network.

9
Example

• ORIGIN 0.6.9.2.3.6.1.4.4.e164.arpa.
• 8.3.0 NAPTR 10 100 "u" "E2Uvoidmailto"
• "!.!mailtonum-drama-info_at_ofcom.org.uk!"
• This indicates that the controller of the number
  block 441632960xxx does not provide telephony
  service via the number 441632960038 it is not
  assigned to an end user.