draft-ietf-spirits-architecture-02.txt   draft-ietf-spirits-architecture-03.txt 
Network Working Group L. Slutsman (Ed.) A new Request for Comments is now available in online RFC libraries.
Internet Draft AT&T Labs
<draft-ietf-spirits-architecture-02.txt> I. Faynberg
Expires October 2001 H. Lu
M. Weissman
Lucent Technologies
The SPIRITS Architecture
Status of this Memo
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Abstract Title: The SPIRITS Architecture
Author(s): L. Slutsman, Editor, I. Faynberg, H. Lu,
M. Weissman
Status: Informational
Date: June 2001
Mailbox: faynberg@lucent.com, huilanlu@lucent.com,
maw1@lucent.com, lslutsman@att.com
Pages: 10
Characters: 19241
Updates/Obsoletes/SeeAlso: None
This document describes the architecture for supporting SPIRITS I-D Tag: draft-ietf-spirits-architecture-03.txt
services, which are those originating in the PSTN and necessitating the
interactions between the PSTN and the Internet. (Internet Call Waiting,
Internet Caller-ID Delivery, and Internet Call Forwarding are examples
of SPIRIT services.) Specifically, it defines the components
constituting the architecture and the interfaces between the components.
1. Introduction URL: ftp://ftp.rfc-editor.org/in-notes/rfc3136.txt
This document describes the architecture for supporting SPIRITS This document describes the architecture for supporting SPIRITS
services, which are those originating in the PSTN and necessitating the services, which are those originating in the PSTN (Public Switched
interactions between the PSTN and the Internet. (Internet Call Waiting, Telephone Network)and necessitating the interactions between the PSTN
Internet Caller-ID Delivery, and Internet Call Forwarding are examples and the Internet. (Internet Call Waiting, Internet Caller-ID
of SPIRIT services.) Specifically, it defines the components Delivery, and Internet Call Forwarding are examples of SPIRIT
constituting the architecture and the interfaces between the services.) Specifically, it defines the components constituting the
components. architecture and the interfaces between the components.
The rest of the document is organized as follows:
+ Section 2 describes example SPIRITS services from the end-user point
of view;
+ Section 3 describes the SPIRITS architecture;
<draft-ietf-spirits-architecture-02.txt> November 2001
+ Section 4 contains security consideration;
+ Section 5 contains acknowledgments;
+ Section 6 contains references; and
+ Appendix contains the figure.
2. Brief Description of Example SPIRITS Services
To illustrate the motivation for the overall SPIRIT architecture,
this section provides a brief description of the example SPIRITS
services:
+ Internet Call Waiting (ICW),
+ Internet Caller-ID Delivery, and
+ Internet Call Forwarding.
These services are considered from the end-user point of view under
the assumptions below:
+ Service subscription (or cancellation) is a separate process and
may be done over the telephone, via postal mail, or over the Web.
+ The subscriber's IP host (e.g., a PC) is loaded with the necessary
software [including a Personal Identification Number (PIN) and the IP
addresses of the SPIRITS servers] for realizing the SPIRITS services.
The software may be sent by postal mail or downloaded from the Web.
+ The subscriber activates a SPIRITS service by an act of service
session registration, which can take place anytime after he (or she)
is connected to the Internet. The subscriber may specify the life
span of the session. As soon as the session ends, the SPIRITS service
is deactivated. Naturally, the subscriber should also be able to
deactivate a SPIRITS service anytime during the service session.
For certain services (such as ICW or Caller-ID Delivery) the
assumption is that the service subscriber has a single telephone line
and a PC, which is connected to the Internet via this telephone.
(Only under this assumption these services make sense.) Nevertheless,
in other services (such as Web-based Call Center, in which a call
center assistant could re-direct or reject a call presented in a
pop-up window) this assumption may be unnecessary or even
inapplicable.
2.1 Internet Call Waiting (ICW)
The Internet call waiting 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.
<draft-ietf-spirits-architecture-02.txt> November 2001
The details of the ICW service lie in the ways that a waiting call
can be treated [1]. Typical ways for handling a call include:
+ Accept the incoming call over the PSTN by terminating the Internet
connection. (As switching cannot be done immediately, the caller may
hear an opening announcement followed by the "ringing" tone.)
+ Forward the incoming call to another telephone number. The
subscriber will remain connected to the Internet, while the caller
will hear an announcement indicating the call is being forwarded and
eventually be connected to the new destination number.
+ Accept the incoming call by voice over IP. The subscriber will
answer the incoming call via the already established Internet
connection. (The proposed SPIRITS architecture, however, does not
reflect this feature.)
+ Redirect the incoming call to voice mail. The subscriber will
remain connected to the Internet, while the caller will hear an
announcement inviting him (or her) to leave a message.
+ Play a pre-recorded message to the calling party and disconnect the
call. The subscriber will remain connected to the Internet.
+ Reject the incoming call. The subscriber will remain connected to
the Internet, while the caller will hear an announcement rejecting
the call.
The subscriber may specify the call treatment on the fly when
notified of an incoming call. Alternatively, the subscriber may
specify a priori a general treatment for all calls (e.g., re-directed
to voice mail) or call treatments tailored to the origination
numbers. As a result, when a call comes in, the subscriber won't be
presented the call but can examine afterwards the treatment and
outcome of the call from the log that is kept for all the calls
processed during the ICW service. Typical information recorded in the
log includes the incoming call date and time, calling party number,
calling party name, and call disposition.
2.2 Internet Caller-ID Delivery
This service allows the subscriber to see the caller's number or name
or both while being connected to the Internet. If the subscriber has
only one telephone line and is using the very line for the Internet
connection, the service is a subset of the ICW service and follows
the relevant description in Section 2.1. Otherwise, the subscriber's
IP host serves as an auxiliary device of the telephone to which the
call is first sent.
2.3 Internet Call Forwarding
The Internet call forwarding service allows a service subscriber to
forward an incoming call to another telephone number while being
connected to the Internet. If the subscriber has only one telephone
<draft-ietf-spirits-architecture-02.txt> November 2001
line and is using the very line for the Internet connection, the
service is a subset of the ICW service and follows the relevant
description in Section 2.1. Otherwise, the subscriber's IP host
serves as an auxiliary device of the telephone to which the call is
first sent.
3. SPIRITS Architecture
Figure 1 of the Appendix depicts the SPIRITS architecture, which
includes the following entities:
1. Service Control Function (SCF) [2], which executes service logic,
interacts with the entities in the IP domain (e.g., the SPIRITS
Gateway and PINT Server) through the SPIRITS Client, and instructs
the switches on how to complete a call. Physically, the SCF may be
located in either stand-alone general-purpose computers called
Service Control Points (SCPs) or specialized pieces of equipment
called Service Nodes (SNs) [2].
2. Service Switching Function (SSF) [2], which normally resides in a
switch and is responsible for the recognition of Intelligent Network
(IN) triggers and interactions with the SCF.
3. SPIRITS Client, which is responsible for receiving PSTN requests
from the SCF as well as sending responses back. It may be co-located
with the SCF. If not, it communicates with the SCF over the D
interface.
4. PINT Server, which receives PINT requests from the PINT Client and
relays them to the PSTN for execution over the E interface.
5. SPIRITS Gateway, which is co-located with the PINT Server or
PINT Gateway (or both when they are co-located as assumed here
for simplicity) and serves as an intermediary between the SPIRITS
Server and SPRITS Client via the B and C interfaces, respectively.
6. PINT Client, which resides in the subscriber's IP host and is
responsible for initiating PINT requests, which are sent to the PINT
server over the A interface.
7. SPIRITS Server, which terminates PSTN requests and is responsible
for all interactions (e.g., incoming call notification and relaying
the call treatment) between the subscriber and the SPIRITS Gateway.
The rest of the Section describes the interfaces between the entities
in detail.
3.1 Interface A
This interface is used for sending PINT requests to PINT Server. Its
principal use is for service session registration and as a result
activation of a SPIRITS service (see Section 2). In addition, this
interface may be used for service subscription.
<draft-ietf-spirits-architecture-02.txt> November 2001
3.2 Interface B
This interface serves two main purposes: 1) to notify the subscriber
of incoming calls together with the calling number and name, if
available; and 2) to send to the SPRITS Gateway the subscriber's
choice of call disposition specified on the fly.
3.3 Interface C
This interface is used for communications between the SPIRITS Client
and SPIRITS Gateway. The SPIRITS Gateway may in turn communicate
with the SPIRITS Server, or may act as a virtual server, terminating
the requests without sending them down to the SPIRITS Server.
3.4 Interface D
This interface is for communications between the SPIRITS Client and
the SCF. Specifically, from the SCF to the SPIRITS Client, the
parameters associated with the applicable IN triggers are sent. From
the SPIRITS Client to SCF, the subscriber's call disposition is sent.
The SCF "transforms" the user's disposition into appropriate actions,
such as playing an announcement to the caller, and resuming the
suspended call processing in the SSP.
3.5 Interface E
This interface is for sending PINT requests to the SCF for execution.
4. Security Considerations
It is assumed that the interface C is between trusting entities. In
addition, the assumption that the PINT Client and SPIRITS Server are
collocated dictates that the security considerations for the A and B
interfaces are exactly the same.
5. Acknowledgments
We would like to thank Alec Brusilovsky, Jorgen Bjorkner, Jim Buller,
Lawrence Conroy, Jorge Gato, Dave Hewins, Naoto Makinae, and Dave
Shrader for their comments and input.
6. References
[1] Lu, H. (Editor), I. Faynberg, J. Voelker, M. Weissman, W. Zhang,
S. Rhim, J. Hwang, S. Ago, S. Moeenuddin, S. Hadvani, S. Nyckelgard,
J. Yoakum, and L. Robart, "Pre-SPIRITS Implementations of PSTN-
Initiated Services ", RFC 2995.
[2] Faynberg, I., L. Gabuzda, M. Kaplan, and N.Shah, "The Intelligent
Network Standards: Their Application to Services", McGraw-Hill, 1997.
<draft-ietf-spirits-architecture-02.txt> November 2001
Appendix
......................
+----------------+ . .
| +------------+ | . +------------+ .
| | | | A . | | .
| | PINT Client|********************|PINT Server/|********
| | | | . Gateway | *
| +------------+ | . +------------+ . *
| | . . *
| Subscriber's | . . *
| | . . *
| IP Host | . . *
| | . +------------+ . *
| +------------+ | . | SPIRITS | . *
| | SPIRITS | | B . | Gateway | . *
| | Server |********************| | . * E
| | | | . +------------+ . *
| +------------+ | . * . *
+----------------+ . * . *
...........*.......... *
//-------\\ * *
/// \\\ * *
| Subscriber's | * C *
| Telephone | * *
\\\ /// * *
\\ -------// * *
* * *
* * *
++++++++++++++++++++++++++ PSTN ++++++++++++++++++++++++++
* * *
* * *
* +------------------+ *
* Line | SPIRITS Client | *
* | | *
+--------------------+ +---+----- D ---------+-*+
| | INAP/SS7 | |
|Service Switching ************Service Control Function |
| Function | | |
| | +-------------------------+
| |
| |
+--------------------+
Figure 1: SPIRITS Architecture
Author's Addresses
Igor Faynberg
Lucent Technologies
Room 4D-601A
101 Crawfords Corner Road
Holmdel, NJ 07733-3030 US
E-mail: faynberg@lucent.com
<draft-ietf-spirits-architecture-02.txt> November 2001
Telephone: +1 732 949 0137
Hui-Lan Lu This document is a product of the Service in the PSTN/IN Requesting
Lucent Technologies Room 4C-607A InTernet Service Working Group of the IETF.
101 Crawfords Corner Road
Holmdel, NJ 07733-3030 US
E-mail: huilanlu@lucent.com
Telephone: +1 732 949 0321
Mark Weissman This memo provides information for the Internet community. It does
Lucent Technologies not specify an Internet standard of any kind. Distribution of this
Room NE406B memo is unlimited.
200 Lucent Lane
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E-mail: maw1@lucent.com
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