rfc2995.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

Network Working Group                                      H. Lu, Editor
Request for Comments: 2995                                   I. Faynberg
Category: Informational                                       J. Voelker
                                                             M. Weissman
                                                                W. Zhang
                                                     Lucent Technologies
                                                                 S. Rhim
                                                                J. Hwang
                                                           Korea Telecom
                                                                  S. Ago
                                                           S. Moeenuddin
                                                              S. Hadvani
                                                                     NEC
                                                           S. Nyckelgard
                                                                   Telia
                                                               J. Yoakum
                                                               L. Robart
                                                         Nortel Networks
                                                           November 2000


         Pre-SPIRITS Implementations of PSTN-initiated Services

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

   This document contains information relevant to the work underway in
   The Services in the PSTN/IN Requesting InTernet Services (SPIRITS)
   Working Group.  It describes four existing implementations of
   SPIRITS-like services from Korea Telecom, Lucent Technologies, NEC,
   and Telia in cooperation with Nortel Networks.  SPIRITS-like services
   are those originating in the Public Switched Telephone Network (PSTN)
   and necessitating the interactions of the Internet and PSTN.









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   Surveying the implementations, we can make the following
   observations:

      o  The ICW service plays the role of a benchmark service.  All
         four implementations can support ICW, with three specifically
         designed for it.

      o  Session Initiation Protocol (SIP) is used in most of the
         implementations as the base communications protocol between the
         PSTN and Internet.  (NEC's implementation is the only exception
         that uses a proprietary protocol.  Nevertheless, NEC has a plan
         to support SIP together with the extensions for SPIRITS
         services.)

      o  All implementations use IN-based solutions for the PSTN part.

   It is clear that not all pre-SPIRITS implementations inter-operate
   with each other.  It is also clear that not all SIP-based
   implementations inter-operate with each other given that they do not
   support the same version of SIP.  It is a task of the SPIRITS Working
   Group to define the inter-networking interfaces that will support
   interoperation of the future implementations of SPIRITS services.

Table of Contents

   1. Introduction ................................................  3
   2. Service Description of Internet Call Waiting ................  4
   3. Korea Telecom's ICW Implementation ..........................  5
   3.1. Overview ..................................................  5
   3.2. Network Architecture ......................................  6
   3.3. Network Entities ..........................................  7
   3.3.1. SSP .....................................................  7
   3.3.2. SCP .....................................................  7
   3.3.3. IP ......................................................  7
   3.3.4. ICW Server System .......................................  7
   3.3.5. ICW Client System .......................................  8
   3.3.6. Firewall ................................................  9
   3.4. Network Interfaces ........................................  9
   3.5. Protocols .................................................  9
   3.5.1. Intelligent Network Application Part Protocol (INAP) ....  9
   3.5.2. PINT Protocol ...........................................  9
   3.6.  Example Scenarios ........................................ 11
   3.6.1. ICW Service Subscription ................................ 11
   3.6.2. ICW Client Installation ................................. 11
   3.6.3. ICW Service Activation .................................. 12
   3.6.4. Incoming Call Notification .............................. 14
   3.6.5. Incoming Call Processing ................................ 15
   3.6.5.1. Accept the Call ....................................... 16



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   3.6.5.2. Forward the Call to Another Number .................... 18
   3.6.6. ICW service De-activation ............................... 20
   4. The Lucent Technologies Online Communications Center ........ 21
   4.1 Overview ................................................... 21
   4.2. Architecture .............................................. 22
   4.3. Protocol and Operations Considerations .................... 25
   5. NEC's Implementation ........................................ 28
   5.1. Overview .................................................. 28
   5.2. Architecture and Overall Call Flow ........................ 29
   5.3. Interfaces and Protocols .................................. 31
   5.3.1. SCP (SPIRITS Client)-SPIRITS Server Interface ........... 31
   5.3.1.1. Connecting to SPIRITS Services ........................ 31
   5.3.1.2. Message Types ......................................... 31
   5.3.1.2.1 Connection Management Message Type ................... 31
   5.3.1.2.2. Data Message Type ................................... 33
   5.3.2. SPIRITS Server-ICW Client Application Interface ......... 34
   5.3.3. Secure Reliable Hybrid Datagram Session Protocol
   (SRHDSP) for Use  .............................................. 35
   5.3.3.1. Overview .............................................. 35
   5.3.3.2. Session Initiation .................................... 35
   5.3.3.3. Secure Reliable Datagram Transport .................... 36
   5.3.3.4. Session closure ....................................... 36
   6. Telia/Nortel's Implementation ............................... 36
   6.1. Overview .................................................. 36
   6.2. Architecture and Protocols ................................ 37
   6.3. Security .................................................. 39
   7. Security Considerations ..................................... 40
   8. Conclusion .................................................. 40
   9. References .................................................. 41
   10. Authors' Addresses ......................................... 41
   11. Full Copyright Statement ................................... 44

1. Introduction

   This document contains information relevant to the work underway in
   The Services in the PSTN/IN Requesting InTernet Services (SPIRITS)
   Working Group.  It describes four existing implementations of
   SPIRITS-like services from Korea Telecom, Lucent Technologies, NEC,
   and Telia in cooperation with Nortel Networks.  SPIRITS-like services
   are those originating in the Public Switched Telephone Network (PSTN)
   and necessitating the interactions of the Internet and PSTN.

   Invariably supported by the implementations examined in this document
   is the Internet Call Waiting (ICW) service.  With ICW, service
   subscribers, while using their telephone lines for Internet access,
   can be notified of incoming voice calls and specify how to handle the
   calls over the same telephone lines.




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   The document first gives a detailed description of the ICW service.
   Then it proceeds to discuss each of the four implementations.  The
   final sections of the document contains security considerations, the
   conclusion and references.

   It is important to note that even though the term "SPIRITS server" is
   used throughout the document, it has no universal meaning.  Its
   connotation depends on the context and varies from implementation to
   implementation.

2. Service Description of Internet Call Waiting

   Internet call waiting is the single service that is specifically
   supported by all the implementations in question.  In a nutshell, the
   service enables a subscriber engaged in an Internet dial-up session
   to

   o  be notified of an incoming call to the very same telephone line
      that is being used for the Internet connection;

   o  specify the desirable treatment of the call; and

   o  have the call handled as specified.

   The details of the ICW service lie in the ways that a waiting call
   can be treated, which vary from implementation to implementation.  In
   this section, we describe the features that are supported by at least
   one of the implementations.  They are as follows:

   o  Incoming Call Notification - The subscriber is notified of an
      incoming call over the Internet, without having any effect on the
      telephone line that is being used by the modem.  When a call comes
      in, the subscriber is presented with a pop-up dialog box on the
      PC.  The dialog box may display any combination of the calling
      party number, calling party name, and calling time.  Note that the
      display of the calling party name (or number) requires the
      availability of the caller name (or number) delivery feature.

   o  Online Incoming Call Disposition - Once informed of the incoming
      call, the subscriber has various options (indicated in the pop-up
      window) for handling the call.  Possible options are:

    + Accepting the call over the PSTN line, thus terminating the
      Internet (modem) connection

    + Accepting the call over the Internet using Voice over IP (VoIP)

    + Rejecting the call



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    + Playing a pre-recorded message to the calling party and
      disconnecting the call

    + Forwarding the call to voice mail

    + Forwarding the call to another number

    + Rejecting (or Forwarding) on no Response - If the subscriber fails
      to respond within a certain period time after the dialog box has
      been displayed, the incoming call can be either rejected or
      handled based on the treatment pre-defined by the subscriber.

   o  Automatic Incoming Call Disposition - Incoming calls are
      automatically handled based on dispositions pre-defined by the
      subscriber without his or her real-time intervention.  The
      subscriber can pre-define the default disposition (e.g., re-
      directed to voice mail) for general calls as well as customized
      dispositions for calls from specific numbers.  In the latter case,
      the subscriber selects a particular disposition for each
      originating number and stores this information in a profile.  When
      a call comes in, the subscriber won't be presented the call but
      can examine the treatment and outcome of the call from the caller
      log (as described in the call logging bullet).  Naturally, this
      feature also allows the subscriber to specify the desired
      treatment for calls originating from private or unpublished
      numbers.

   o  Multiple Call Handling - Multiple calls can arrive during call
      disposition processing.  With multiple call handling, the
      subscriber is notified of the multiple calls one by one.

   o  Call Logging - A detailed log of the incoming calls processed
      during the ICW service is kept.  Typical information recorded in
      the log include the incoming call date and time, calling party
      number, calling party name, and call disposition.

3. Korea Telecom's ICW Implementation

3.1. Overview

   Korea Telecom's ICW implementation supports most of the features
   described in Section 2.  (The major exception is the feature of
   receiving the incoming call over the Internet using voice over IP.)
   In addition, the Korea Telecom implementation supports flexible
   activation and de-activation of the ICW service:






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   o  Automatic Activation/De-activation - When Internet dial-up
      connection is set up, the ICW service is activated or de-activated
      automatically.

   o  Manual Activation/De-activation - The subscriber can de-activate
      the ICW service manually when call notification is not desired
      during the Internet dial-up session and activate it when needed.

3.2. Network Architecture

   Figure 1 depicts the network architecture of the Korea Telecom ICW
   service.  The Service Switching Point (SSP), Service Control Point
   (SCP), and Intelligent Peripheral (IP) are legacy PSTN IN elements
   based on IN CS-1.  In contrast, both the ICW Server System and the
   ICW Client System are new network elements that are installed in the
   Internet domain to support of the ICW service.

     +---------------------------+      |     +--------------+
     |+--------+propr-+---------+| PINT |     |(Proxy Server)|  PINT
     ||(ICW SL)|ietary|(UAC/UAS)||--- -||-----|     ICW      |----+
     ||SCF/SDF |------|  SCGF   ||   firewall |Server System |    |
     |+--------+ i/f  +---------+|      |     +------------- +    |
     |           SCP             |      |                         |
     +------+--------------+-----+      |                         |
            |INAP          |INAP        |              firewall=====
            |              |            |                         |
        +---+---+      +---+---+                                  |
        |  IP   |      |  SSP  |                                  |
        +-------+      +---+---+                        +-------------+
                           |                   +---+    |  (UAC/UAS)  |
                       +---+---+              ||   ||   |    ICW      |
             |---------|  LEX  |--------------  + +     |Client System|
           +---+       +-------+               +++++----+-------------+
          ||   ||                             (callee)
            + +                           ICW Subscriber's Phone and PC