draft-ietf-enum-e164-gstn-np-01.txt

bind-3.2.

                                                            Mark Foster 
Internet Draft                                              Tom McGarry 
Document: <draft-ietf-enum-e164-gstn-np-01.txt>                James Yu 
                                                          NeuStar, Inc. 
Category: Informational                                February 9, 2001 
 
 
              Number Portability in the GSTN: An Overview 
 
 
Status of this Memo 
 
   This document is an Internet-Draft and is in full conformance with 
   all provisions of Section 10 of RFC2026 [RFC].  
 
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1. Abstract 
    
   This document provides an overview of E.164 telephone number 
   portability (NP) in the Global Switched Telephone Network (GSTN).  
   There are three types of number portability: service provider number 
   portability (SPNP), location portability, and service portability.  
   Service provider portability, the focus of the present draft, is a 
   regulatory imperative in many countries seeking to liberalize local 
   telephony service competition, by enabling end-users to retain pre-
   existing telephone numbers while changing service providers.  
   Implementation of NP within national GSTN entails potentially 
   significant changes to numbering administration, network element 
   signaling, call routing and processing, billing, service management, 
   and other functions.  NP changes the fundamental nature of a dialed 
   E.164 number from a hierarchical physical routing address to a 
   virtual address, thereby requiring the transparent translation of 
   the later to the former.  In addition, there are various regulatory 

  
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Number Portability in the GSTN: An Overview           February 9, 2000 
 
 
   constraints that establish relevant parameters for NP 
   implementation, most of which are not network technology specific.  
   Consequently, the implementation of NP behavior consistent with 
   applicable regulatory constraints, as well as the need for 
   interoperation with the existing GSTN NP implementations, are  
   relevant topics for numerous areas of IP telephony work-in-progress 
   at IETF. 
 
    
2. Introduction 
    
   This document provides an overview of E.164 telephone number 
   portability in the Global Switched Telephone Network (GSTN).  There 
   are considered to be three types of number portability (NP): service 
   provider portability (SPNP), location portability (not to be 
   confused with terminal mobility), and service portability. 
    
   Service provider portability (SPNP), the focus of the present draft, 
   is a regulatory imperative in many countries seeking to liberalize 
   telephony service competition, especially local service.  
   Historically, local telephony service (as compared to long distance 
   or international service) has been regulated as a utility-like form 
   of service.  While a number of countries had begun liberalization 
   (e.g. privatization, de-regulation, or re-regulation) some years 
   ago, the advent of NP is relatively recent (since ~1995). 
    
   E.164 numbers can be non-geographic and geographic numbers.  Non-
   geographic numbers do not reveal the locations information of those 
   numbers.  Geographic E.164 numbers were intentionally designed as 
   hierarchical routing addresses which could systematically be digit-
   analyzed to ascertain the country, serving network provider, serving 
   end-office switch, and specific line of the called party.  As such, 
   without NP a subscriber wishing to change service providers would 
   incur a number change as a consequence of being served off of a 
   different end-office switch operated by the new service provider.  
   The cost and convenience impact to the subscriber of changing 
   numbers is seen as barrier to competition.  Hence NP has become 
   associated with GSTN infrastructure enhancements associated with a 
   competitive environment driven by regulatory directives. 
    
   Forms of SPNP have been deployed or are being deployed widely in the 
   GSTN in various parts of the world, including the U.S., Canada, 
   Western Europe, Australia, and the Pacific Rim (e.g. Hong Kong). 
   Other regions, such as South America (e.g. Brazil) are actively 
   considering it. 
    
   Implementation of NP within a national telephony infrastructure 
   entails potentially significant changes to numbering administration, 
   network element signaling, call routing and processing, billing, 
   service management, and other functions. 
    
   NP changes the fundamental nature of a dialed E.164 number from a 
   hierarchical physical routing address to a virtual address.  NP 
  
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Number Portability in the GSTN: An Overview           February 9, 2000 
 
 
   implementations attempt to encapsulate the impacts to the GSTN and 
   make NP transparent to subscribers by incorporating a translation 
   function to map a dialed, potentially ported E.164 address, into a 
   network routing address (either a number prefix or another E.164 
   address) which can be hierarchically routed. 
    
   This is roughly analogous to the use of network address translation 
   on IP addresses to enable IP address portability by containing the 
   impact of the address change to the edge of the network and retain 
   the use of CIDR blocks in the core which can be route aggregated by 
   the network service provider to the rest of the internet. 
    
   NP bifurcates the historical role of a subscriber苨 E.164 address 
   into two or more data elements (a dialed or virtual address, and a 
   network routing address) that must be made available to network 
   elements through an NP translations database, carried by forward 
   call signaling, and recorded on call detail records.  Not only is 
   call processing and routing affected, but also so is SS7/C7 
   messaging.  A number of TCAP-based SS7 messaging sets utilize an 
   E.164 address as an application-level network element address in the 
   global title address (GTA) field of the SCCP message header.  
   Consequently, SS7/C7 signaling transfer points (STPs) and gateways 
   need to be able to perform n-digit global title translation (GTT) to 
   translate a dialed E.164 address into its network address 
   counterpart via the NP database. 
    
   In addition, there are various national regulatory constraints that 
   establish relevant parameters for NP implementation, most of which 
   are not network technology specific.  Consequently, implementations 
   of NP behavior in IP telephony consistent with applicable regulatory 
   constraints, as well as the need for interoperation with the 
   existing GSTN NP implementations, are relevant topics for numerous 
   areas of IP telephony work-in-progress at IETF. 

   This document describes three types of number portability and the 
   four schemes that have been standardized to support SPNP for 
   geographic E.164 numbersspecifically.  Following that, specific 
   information regarding the call routing and database query 
   implementations are described for several regions (North American 
   and Europe) and industries (wireless vs. wireline). The Number 
   Portability Database (NPDB) interfaces and the call routing schemes 
   that are used in the North America and Europe are described to show 
   the variety of standards that may be implemented worldwide.  A 
   glance of the NP implementations worldwide is provided.  Number 
   pooling is briefly discussed to show how NP is being enhanced in the 
   U.S. to conserve North American area codes.  The conclusion briefly 
   touches the potential impacts of NP on IP & Telecommunications 
   Interoperability.  Appendix A provides some specific technical and 
   regulatory information on NP in North America.  Appendix B describes 
   the number portability administration process that manages the 
   number portability database in North America. 
    
    
  
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Number Portability in the GSTN: An Overview           February 9, 2000 
 
 
3. Abbreviations and Acronyms 
    
   ACQ     All Call Query 
   AIN     Advanced Intelligent Network 
   AMPS    Advanced Mobile Phone System 
   ANSI    American National Standards Institute 
   CDMA    Code Division Multiple Access 
   CdPA    Called Party Address 
   CdPN    Called Party Number 
   CH      Code Holder 
   CMIP    Common Management Information Protocol 
   CS1     Capability Set 1 
   CS2     Capability Set 2 
   DN      Directory Number 
   DNS     Domain Name System 
   ETSI    European Technical Standards Institute 
   FCI     Forward Call Indicator 
   GAP     Generic Address Parameter 
   GMSC    Gateway Mobile Services Switching Center or Gateway Mobile 
           Switching Center 
   GSM     Global System for Mobile Communications 
   GSTN    Global Switched Telephone Network 
   GW      Gateways 
   HLR     Home Location Register 
   IAM     Initial Address Message 
   IETF    Internet Engineering Task Force 
   ILNP    Interim LNP 
   IN      Intelligent Network 
   INAP    Intelligent Network Application Part 
   INP     Interim NP     
   IP      Internet Protocol 
   IS-41   Interim Standards Number 41 
   ISDN    Integrated Services Digital Network 
   ISUP    ISDN User Part 
   ITN     Individual Telephony Number  
   ITU     International Telecommunication Union 
   ITU-TS  ITU-Telecommunication Sector 
   LDAP    Lightweight Directory Access Protocol  
   LEC     Local Exchange Carrier 
   LNP     Local Number Portability 
   LRN     Location Routing Number 
   MAP     Mobile Application Part 
   MNP     Mobile Number Portability 
   MSRN    Mobile Station Roaming Number 
   MTP     Message Transfer Part 
   NANP    North American Numbering Plan 
   NP      Number Portability 
   NPDB    Number Portability Database 
   NRN     Network Routing Number 
   OR      Onward Routing 
   OSS     Operation Support System 
   PCS     Personal Communication Services 
   PNTI    Ported Number Translation Indicator 
  
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   PODP    Public Office Dialing Plan 
   PUC     Public Utility Commission 
   QoR     Query on Release 
   RN      Routing Number 
   RTP     Return to Pivot 
   SCCP    Signaling Connection Control Part 
   SCP     Service Control Point  
   SIP     Session Initiation Protocol 
   SMR     Special Mobile Radio 
   SMS     Service Management System 
   SPNP    Service Provider Number Portability 
   SRF     Signaling Relaying Function 
   SRI     Send Routing Information 
   SS7     Signaling System Number 7 
   STP     Signaling Transfer Point 
   TCAP    Transaction Capabilities Application Part 
   TDMA    Time Division Multiple Access 
   TN      Telephone Number 
   TRIP    Telephony Routing Information Protocol