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BLISS                                                   T. Zourzouvillys
Internet-Draft                                                VoIP.co.uk
Intended status: Informational                          October 24, 2008
Expires: April 27, 2009


        Automatic Call Handling (ACH) Configuration Requirements
          draft-zourzouvillys-bliss-ach-config-requirements-00

Status of this Memo

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   This Internet-Draft will expire on April 27, 2009.

Abstract

   This document examines the requirements for a protocol that allows an
   agent to configure an ACH enabled proxy.













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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Requirements notation . . . . . . . . . . . . . . . . . . . . . 3
   3.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   4.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   5.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   6.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . . . 4
     6.1.  High Level Requirements . . . . . . . . . . . . . . . . . . 4
       6.1.1.  Discovery . . . . . . . . . . . . . . . . . . . . . . . 4
       6.1.2.  Settings Manipulation . . . . . . . . . . . . . . . . . 4
       6.1.3.  Optional: Multiple Profiles . . . . . . . . . . . . . . 4
       6.1.4.  Conflict Detection  . . . . . . . . . . . . . . . . . . 5
       6.1.5.  Agent Notifications . . . . . . . . . . . . . . . . . . 5
       6.1.6.  Error Detection . . . . . . . . . . . . . . . . . . . . 5
       6.1.7.  Extending Settings  . . . . . . . . . . . . . . . . . . 5
     6.2.  Profile Requirements  . . . . . . . . . . . . . . . . . . . 5
       6.2.1.  Conditions  . . . . . . . . . . . . . . . . . . . . . . 5
       6.2.2.  Semantic Meaning  . . . . . . . . . . . . . . . . . . . 5
       6.2.3.  Extending Profiles  . . . . . . . . . . . . . . . . . . 6
       6.2.4.  NAT Traversal . . . . . . . . . . . . . . . . . . . . . 6
       6.2.5.  Security  . . . . . . . . . . . . . . . . . . . . . . . 6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 7
   9.  Normative References  . . . . . . . . . . . . . . . . . . . . . 7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 7
   Intellectual Property and Copyright Statements  . . . . . . . . . . 8
























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1.  Introduction

   Automatic Call Handling (ACH) provides support for SIP proxies to
   apply automatic treatment to calls, as described in [I-D.ietf-bliss-
   ach-analysis].

   In order to encourage interoperability, a protocol is needed for User
   Agents (or agents acting on behalf of the user) to be able to
   configure a proxy to apply treatment to calls.

   This document analyzes the requirements needed for such a protocol.


2.  Requirements notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].


3.  Scope

   This document examines a range of requirements for an agent running
   on behalf of a user served by an ACH enabled proxy to be able to
   configure the proxy.

   This document only discusses the requirements for such functionality.
   A separate document will address solutions.


4.  Definitions

      Agent- A client acting on behalf of a user
      Profile - A set of configuration parameters that define what
      treatment should be applied to incoming calls.


5.  Overview

   ACH provides functionality for a SIP proxy hosted on a network to
   provide services on behalf of a user, for example to reject a call or
   forward it as needed.

   Currently, SIP vendors each define their own out of band methods for
   configuring these call handling rules - commonly via a web interface
   or an IVR application.  Both of these examples have the drawback that
   they are suitable for use by a human user, but not for an agent
   acting on behalf of a user or automata.



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   The ACH configuration mechanism will provide a mechanism more suited
   for use by a user's agent to modify the configuration on the proxy.
   This then allows an agent to present the user with an interface
   suitable to the device for manipulating this information, or an
   automaton acting on behalf of a user running somewhere within the
   network.


6.  Requirements

6.1.  High Level Requirements

6.1.1.  Discovery

   REQ: Given a SIP AOR, an agent should be able to discover where to go
   to retrieve the ACH configuration settings.

6.1.2.  Settings Manipulation

   REQ: It must be possible for an agent to add new ACH settings.

   REQ: It must be possible for an agent to modify existing ACH
   settings.

   REQ: It must be possible for an agent to delete existing ACH
   settings.

6.1.3.  Optional: Multiple Profiles

   An optional part of the ACH configuration could allow multiple
   profiles to be configured on the server.  An agent would then be able
   to switch between profiles without needing to know the configuration
   itself, by selecting the profile in the main configuration.

   This would be useful for a SIP UA without a UI - the active profile
   could be selected without needing an interface, and would not need to
   implement logic for manipulation of profiles, as this could be done
   using a UA with a display.

   It also allows a user with multiple devices to keep multiple
   profiles, and a change to the profile on one device would not need to
   be made on all devices.

   REQ: A means may be defined to allow multiple profiles to be created
   and stored on the server, and choose an active one for call
   treatment.





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6.1.3.1.  Active Profile

   REQ: An agent must be able to discover the active profile given an
   AOR and valid credentials for accessing it.

6.1.3.2.  Profile Manipulation

   REQ: It must be possible for an agent to define new profiles, list,
   modify, and delete existing ones.

6.1.4.  Conflict Detection

   REQ: An agent must be able to fetch settings or a profile, modify
   them, and re-upload without any risk of conflicts.  It must also be
   able to fetch the active profile, and attempt to change it without
   any risk of conflict from another agent attempting to also change the
   profile in the process.

6.1.5.  Agent Notifications

   REQ: An agent should be able to register it's interest in receiving
   updates to settings for a given user.

6.1.6.  Error Detection

   REQ: A server must have functionality for returning descriptive
   errors back to the agent when attempting to modify settings.

6.1.7.  Extending Settings

   REQ: It must be possible for vendors to define extensions to the
   settings in a way that will not conflict with other vendors settings.

6.2.  Profile Requirements

6.2.1.  Conditions

   REQ: Apply different treatment based on sets of conditions:
   (1)  Response code from sending call to a binding
   (2)  Caller Identity
   (3)  Time of day or week
   (4)  Specific set of date/time periods

6.2.2.  Semantic Meaning

   An agent should be able to download a profile uploaded by another
   agent from another vendor and be able to render an interface to a
   user to allow them to change the settings, or alter a UI based on the



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   configuration - for example to illuminate an "call divert enabled"
   lamp.

   REQ: An agent must be able to extract the semantic meaning in a
   simple manner from an ACH configuration profile after fetching it.

6.2.3.  Extending Profiles

   REQ: It must be possible to define extensions to the configuration
   format to define new primitive conditions or actions for call
   treatment within profiles.

6.2.4.  NAT Traversal

   It is important that agents behind NAT will function correctly, both
   for direct configuration manipulation, and also for notifications of
   configuration changes.

   REQ: An agent must be fully functional behind NAT.

6.2.5.  Security

   It is possible that a SIP proxy only has access to the RFC 2617 HA1
   value of a user's credentials.

   REQ: Both the agent and server MUST support Digest authentication for
   authenticating the agent based on the same credentials used by a SIP
   user agent for registration operations.

   REQ: An agent must be able to validate the identity of the server in
   a secure fashion.

   REQ: Data transfered between the agent and server must have integrity
   protection.

   REQ: Data transfered between the agent and server must be secured
   from eavesdropping.


7.  Security Considerations

   All operations described in this document should be subject to
   appropriate security, the requirements for which are stated earlier
   in the document.







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8.  Acknowledgements

   The following individuals were part of the ACH Team, and have helped
   to shape this document:

   Christian Schmidt, John Elwell, John Zhao, Michael Procter, Shida
   Schubert, and Martin Dolly.


9.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.


Author's Address

   Theo Zourzouvillys
   VoIP.co.uk
   Commerce House
   Telford Road
   Bicester, Oxfordshire  OX26 4LD
   UK

   Phone: +44 1908 764196
   Email: theo@voip.co.uk
   URI:   http://voip.co.uk




















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Full Copyright Statement

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