Need for PSTN Internet Notification (PIN) Services [Page 1] A. Brusilovsky Internet Draft V. Gurbani A. Jain D. Varney Lucent Technologies Expires: November 1999 Need for PSTN Internet Notification (PIN) Services A Proposal for a new Working Group Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. 1. Abstract The purpose of this Internet Draft is to start discussion on the issues involved in PSTN Internet Notification (PIN), as part of interconnecting IP and Public Switched Telephone Network (PSTN) with the intent of converging existing and creating new hybrid PSTN and IP services. PSTN Events Notification, based on open well-defined protocols, will promote interoperability of both the networks and systems built by different vendors. This Internet Draft is submitted with the goal of becoming an informational RFC. The rest of this document is as follows: Section 2 briefly describes the PIN services. Section 3 describes the scope of the proposed project by introducing February 1999 Need for PSTN Internet Notification (PIN) Services [Page 2] its overall architecture and identifying the interfaces to be standardized. Sections 4, 5, and 6 respectively address security considerations, supply references, and provide the authors address, as required by [1]. Section 7 acknowledges individuals providing assistance in the creation of this document. 2. PIN Description Current PSTN/Internet Interfaces (PINT) WG addresses connection arrangements through which Internet applications can request and enrich PSTN (Public Switched Telephone Network) telephony services. Some Interworking services require Notification and requests for services that come from PSTN/IN. Essentially, these requests will be "mirror image" of PINT requests. To provide interoperability between PSTN and IP networks, it is very important to ensure notification to IP network of the events happening in PSTN. PSTN/IN Call Flow is organized around actions or collections of actions called Point-In-Call (PIC). Detection Points (DPs), which are associated with the PICs, operate between the PICs, and can be the basis for Notification Events for Interworking with IP network. IN furnishes "Network Intelligence" to PSTN. Similarly, it can be utilized to initiate Notification Events to IP network. PSTN/IN events can be grouped into two categories: Basic events: 1. Phone off-hook. 2. Phone on-hook. 3. Voice-mail Arrival. 4. Incoming Call Notification (Attempt to Terminate Call). Advanced events: 1. Attempt to dial number (specific event can be Attempt to Dial ISP Number. 2. Dropping Dialed Connection (i.e. dropping ISP call). 3. ISP Connection Made. 4. Attempt to Forward Call (forwarded end point could easily be VoIP terminal). 5. Attempt to Subscribe/Unsubscribe for a PSTN Service (i.e. Set Up Call Forwarding). 6. Attempt to Enter Conference. (Notification only) 7. Attempt to Exit Conference. (Notification only) 8. Identification of the Speaker (talking party) to the other participants of the Voice (or multimedia) Conference (Notification only). February 1999 Need for PSTN Internet Notification (PIN) Services [Page 3] Examples of services that are based on PIN, or use PIN as one of the building blocks are: 1. Internet Call Waiting. ICW is the capability to provide incoming call notification and completion options when the Subscriber is on a dial-up IP connection. 2. Internet Call Management. PSTN call notification and control options (flexible call screening, forwarding, etc.), delivered to an IP client. 3. Internet Conference Management. PSTN Teleconference notification and management from an IP Client 4. Internet Conference Mediation. Pre-Teleconference (before an actual connection is made) management service from an IP client. 5. Advanced Caller ID Delivery [7]. Ordered incoming call notification to multiple Subscriber's dial-up IP connections. 6. Queue Management. Notification of the status and events of the call queue, much needed for the IP-based Call Center Control. 7. Call Progress Delivery as part of PINT services. Classic PINT services need notification of the Call Progress. 8. Internet Call Routing (ICR). Flexible routing and control over a dial up PSTN call from an IP host. 3. Proposed Architecture With the proliferation and wide acceptance of the Internet, and more so with the convergence of the Internet and PSTN, there is an increasing desire for events occurring on the PSTN domain to be propagated to the Internet domain. The PIN protocol attempts to fill this void. Entities on the Internet domain can receive the events generated by the PSTN domain and act appropriately. The major entities that comprise of the PIN protocol are the PIN gateway, the PIN server and various PIN clients, as depicted in Figure 1. --------- PSTN ; IP | PIN | Domain ; Domain ----| Client | ; --------- | | | ; | PIN |---- --------- ; .-.-| Server | --------- --------- : | |---- --------- | | | PIN |-.-. --------- | | PIN | | SNF |....| Gateway | ----| Client | | | | |-.-. --------- | | --------- --------- : | PIN | --------- ; .-.-| Server | ; | | ; --------- ; February 1999 Need for PSTN Internet Notification (PIN) Services [Page 4] Figure A illustrates the functional scalable architecture that will support PIN Services. Legend: SNF - Service Notification Function .-. - PIN Protocol --- - Standard Client/Server Protocol or, potentially, PIN Protocol ... - Standard PSTN/SS7/IN Protocol Service Notification Function (SNF) is located in PSTN domain and physically can reside in IN elements (SCP, SMS, SSP) that are specialized servers, connected to switches and other PSTN elements [3]. SNF (PSTN) informs the PIN Gateway of the PSTN events utilizing traditional protocols (SS7/IN). PIN Gateway then relays these events to one or more PIN Servers. PIN Server provides Subscription for Notification Services and aggregates Notification events for PIN Clients. A PIN Client is an IP end-point, which has subscribed for PIN services with one or more PIN Servers. PIN protocol is a specialized protocol used for communication between the PIN gateway and PIN servers, which may, potentially, be used for communications between PIN Servers and PIN Clients. We are proposing new Working Group to be a "mirror image" of the PINT WG, regarding direction of the requests for service and dealing with Notification only. Like PINT, PIN will not deal with IP Telephony, but rather provide requests for services and Notifications from PSTN/IN to IP network in order to augment, extend and enrich PSTN. PIN WG will focus on the PIN Protocol Requirements and, optionally, Definition of Notification Processing Language (NPL), a possible extension to CPL, as well as defining connections of the Notification Services to the IN DPs. NPL will allow to build new Notification Services and provide means to describe Notification Filters for Notification screening. (Notification Filter example: Notification for an Attempt to Enter Conference from a predefined number in the hours 9 through 17 only on weekends and holidays.) It is quite possible that existing or under development protocols (i.e. SIP, PIP [8], MGCP, etc.) are sufficient to support PIN Services, but that determination is for further study. 4. Security Considerations PIN communications between the PIN Client, PIN Server, PIN Gateway and the SNF may travel over the Internet. Thus it is essential to provide encryption for the communications. In addition to encryption, it is also necessary to provide authentication of both the end points; i.e. SNF and PIN Client. PIN security has to authenticate both end points and if the authentication succeeded, encrypt the communications. February 1999 Need for PSTN Internet Notification (PIN) Services [Page 5] PIN Security Requirements are, essentially, the same as PINT Security Requirements outlined in [4]: o Peer entity authentication to allow a communicating entity to prove its identity to another in the network. o Non-repudiation to account for all operations in case of doubt or dispute. This could be achieved by logging all the information pertinent to the transaction. In addition, the PSTN network will maintain its own account of the transaction for generating bills. o Confidentiality to avoid disclosure of information without the permission of its owner. Although this is an essential requirement, it is not particular to the proposed project. o PIN Client profile verification to verify if the end user is authorized to use a service. In the course of the project execution, additional requirements are likely to arise and many more specific security work items are likely to be proposed and implemented. Some of the PIN-specific security considerations: o Cracking is a threat to any Service Provider (PSTN, Intranet, Internet). It is real danger - phone companies are common targets o Notification spoofing is one of the threats o Existing mechanisms applied to the Internet can be implemented o Stealing a Notification is a new type of security threat 5. References [1] J. Postel, RFC 1543, "Instruction to RFC Authors". October 1993 [2] ITU-T Q.12xx Recommendation Series, Geneva, 1995. [3] I. Faynberg, L. R. Gabuzda, M. P. Kaplan, and N. J. Shah, "The Intelligent Network Standards, their Application to Services". McGraw-Hill, 1996. [4] S. Petrack, "IP Access to PSTN Services: Basic Service Requirements, Definitions, and Architecture", Internet Draft [5] Handley, Schulzrinne, Schooler, Rosenberg, "SIP: Session Initiation Protocol", Internet Draft [6] "Proposal for Internet Call Waiting Service using SIP", Internet Draft [7] L.Slutsman, "Advanced Internet Caller ID Delivery Service", February 1999 Need for PSTN Internet Notification (PIN) Services [Page 6] Internet Draft [8] J.Rosenberg, H.Schulzrinne, "SIP For Presence", Internet Draft [9] S.Bradner, "The Internet Standards Process", RFC2026 6. Authors' Address Alec Brusilovsky E-mail: abrusilovsky@lucent.com Telephone: +1-630-713-8401 Fax: +1-630-713-5840 Lucent Technologies 263 Shuman Blvd. Naperville, IL 60566 USA Vijay Gurbani E-mail: vkg@lucent.com Telephone: +1-630-224-0216 Fax: +1-630-713-5840 Lucent Technologies 263 Shuman Blvd. Naperville, IL 60566 USA Ajay Jain E-mail: ajayjain@lucent.com Telephone: +1-630-979-5218 Fax: +1-630-713-5840 Lucent Technologies 263 Shuman Blvd. Naperville, IL 60566 USA Doug Varney E-mail: dvarney@lucent.com Telephone: +1-630-979-8750 Fax: +1-630-713-5840 Lucent Technologies 263 Shuman Blvd. Naperville, IL 60566 USA Glossary CPL Call Processing language DN Destination Number DP Detection Point ICW Internet Call Waiting IN Intelligent Network MGCP Media Gateway Control Protocol NPL Notification Processing Language February 1999 Need for PSTN Internet Notification (PIN) Services [Page 7] PIC Point-In-Call PSTN Public Switched Telephone Network SCP Service Control Point SIP Session Initiation Protocol SN Service Node VoIP Voice over IP (Internet Protocol) 7. Acknowledgments The authors would like to acknowledge Lawrence Conroy, Igor Faynberg, Hui-Lan Lu, Shehryar Qutub, Jonathan Rosenberg and Lev Slutsman for their contributing to the creation of this document. February 1999