ABRIDGED VERSION OF THE

1 April 1997

DRAFT OF THE

 

NORTH AMERICAN NUMBERING PLAN

EXPANSION REPORT

OF THE

INDUSTRY NUMBERING COMMITTEE

 

EMENDED TO ASCERTAIN COMPATIBILITY WITH THE

MULTIFUNCTIONAL TELECOMMUNICATION ADDRESSING SYSTEM

 


TABLE OF CONTENTS

1.0 PURPOSE & SCOPE

2.0 ASSUMPTIONS & CONSTRAINTS

3.0 FUNCTIONALITIES

4.0 ASSESSMENT CRITERIA

5.O DESCRIPTION OF NANP EXPANSION OPTIONS

6.0 PROS & CONS/ELIMINATIONS

7.0 DEPENDENCIES, TIMING and TRIGGERS

8.0 PLAN UPDATE PROCEDURES/RESPONSIBILITIES

9.0 OTHER FORA/WORKSHOPS IMPACTED

10.0 RECOMMENDED EXPANSION PLAN

11.0 IMPLEMENTATION TIMING AND TRANSITION PLAN

ANNEX A - EXISTING NANP FORMAT & RESTRICTIONS

ANNEX B - APPENDIX 'J' - LTNP VERSION 2 1/4/93

ANNEX C - ELIMINATED OPTIONS/RATIONALE

ANNEX D - OTHER NANP EXPANSION PROPOSALS CONSIDERED

ANNEX E - NANC NPA EXHAUST PROJECTION

ANNEX F - NANP EXPANSION PROJECT WORK PROGRAMME


Return to Compatibility Issues


1.0 PURPOSE AND SCOPE - The NANP Expansion Report, developed through the Industry Numbering Committee concensus process, is intended to provide a detailed roadmap of the procedures required to expand the NANP to meet the long term needs of the telecommunications industry and the user community in the geographic area served by the NANP, which will be referred to as the Long Term Numbering Plan.

The plan will document the expansion options and process requirements in both the 10 digit NANP environment, and, when expansion beyond the current 10 digit limit is required. The plan will define the numerical expansion requirements, as well, it will identify the transition strategies, trigger points and dependencies required to ensure the smooth and timely evolution of the NANP.

The NANP Expansion Plan is intended to be a living document which is to be kept current by the industry through regularly scheduled updates, or, action trigger mechanisms which are to be identified and maintained in the document.


2.0 ASSUMPTIONS AND CONSTRAINTS - The following is a list of proposed assumptions and constraints for NANP expansion efforts.

1. The digits of the NANP will be of the decimal system (i.e. 0-9).

MTAS compatible.

2. The control characters, star (* ) and number sign (#), will continue to be used only as control characters to indicate a special dialing/addressing function.

MTAS markers <*> and <#> used as control characters only for device identification.

3. The dial/keyboard/keypad on basic terminals will remain functionally unchanged.

MTAS compatible.

4. The basic function of manual "dialing" must be maintained (i.e. automatic input will not become universal).

MTAS compatible.

5. The expanded NANP will be consistent with ITU Recommendation E.164 (Public Telecommunications Numbering Plan).

The structure of the ITU Recommendation E.164 number is made up of the following fields

1 to 3 Digits Max (15 - n) Digits

National (Significant) Number

Max 15 Digits

International Public Telecommunication

Number for Geographic Areas

Where:
CC = Country Code
NDC = National Destination Code
SN = Subscriber Number
15 - n = n equals the number of digits in the Country Code

6) The length of the National (Significant) Number in the expanded NANP will be limited to 12 digits. This is to ensure compliance with ITU Recommendation E.164 which allows for a maximum length of 3 digits for the country code within the maximum length of 15 digits for the International Number."

MTAS compatible with international calling when address is limited to two markers (<##>. Maximum of two markers permit six devices to be accessed.

7) The expanded NANP resources will continue to be assigned to and used exclusively by service providers and users who reside in the countries that form the NANP community.

MTAS compatible.

8) The expanded NANP must provide for adequate numbering resources for a competitive environment within any of the countries served by the NANP.

MTAS compatible.

9) The expanded NANP must increase the quantity of NPAs in order to ensure the availability of additional NPAs when the current supply is exhausted

MTAS compatible.

10) The expanded NANP must mitigate the need for future NPA relief.

MTAS compatible.

11) The expanded NANP shall support the Public Switched Telephone Network. Private numbering plans are not accommodated by these NANP resources. Existing and future services' interfaces and network capabilities should be supported by the expanded numbering resource.

MTAS compatible.

12) The expanded NANP should be implementable with sufficient time to permit both an orderly transition to the expanded format and provide sufficient numbering resources to meet industry requirements.

MTAS compatible.

13) The expanded NANP must meet applicable national regulatory or governmental requirements (e.g. number portability) in effect at the time the expanded NANP is implemented.

MTAS compatible.

14) The NANP expansion plan must apply throughout the NANP serving area subject to the appropriate regulatory or governmental procedures and constraints. In order to remain part of the NANP each country must implement the accepted NANP expansion plan.

MTAS compatible.

15) The expanded NANP should not be constrained by the current practice of assigning line numbers in blocks of ten thousand to switching entities or points of interconnection (POI).

MTAS compatible.

16) The expanded NANP must support service provider number portability in both geographic and non-geographic applications. The following assumptions apply to the portability of geographic numbers:

a) NPAs will retain geographic significance (i.e., user perceived territories)

MTAS compatible.

b) portability with pooling will at a minimum cover the top 100 MSAs

MTAS compatible.

c) portability and pooling in general will not be permitted across numbering plan area boundaries (Note: Where local calling areas cross state boundaries and/or include multiple NPAs, portability may be supported.)

MTAS compatible.

d) portability will apply to all geographic numbers used in a wireline/wireless environment

MTAS compatible.

e) location portability will be supported throughout any given portability pooling area and will not be restricted to rate centers

MTAS compatible.

f)While service provider portability refers to the ability of end users to retain the same telephone number as they change from one service provider to another, service portability refers to the ability of users of telcommunications services to retain existing telcommunications numbers without impairment of quality, reliability or convenience when switching from one tecommunications service to another service (i.e. POTS to ISDN) provided by the same telcommunications carrier

MTAS compatible.


3.0 NANP FUNCTIONALITY - The NANP supports the provision of a basic set of functionalities which are described in Section 3.1. The key function provided by the NANP number set itself is user access and, user derived information relevant to that access (e.g. a 213 number is located in Los Angeles, an 800 call is "free", etc.). The ability to use the NANP number to derive the specific information required to perform traditional functions is a product of systematic intelligence provided in the network's infrastructure. In short, the numbering plan is an enabler, and, not a direct provider of most network functions. However, some of the network's most fundamental capabilities are supported in this manner (i.e. rating,
routing, billing, etc.).

Therefore, when considering the merits of existing and future NANP based "functionalities", one must consider the impact on existing or new network infrastructure (i.e. switching, billing systems, etc.) to support such functionality.

3.1 Exisiting Functions - The existing NANP supports the following functionalities:

Terminal Identification - A NANP number uniquely identifies the network service access point/interface for each PSTN terminal in terms of identifying the local switch and the specific switch facilities associated with that terminal

MTAS compatible.

Personal Identification - When a NANP number is used for personal identification, it uniquely identifies an individual/ person. Call delivery/routing is controlled by a service profile management capability which directs/routes the calls to a terminating point (typically identified by another NANP number) chosen by the called party. SAC 500 is currently available for this type of application.

MTAS compatible.

Service Identification - Service identification using NANP numbers is the association between a number and a service. An example is that calls to 800 numbers are "toll-free" to the calling party.

MTAS compatible.

Geographic Significance - For example, the assignment of NPA codes to a specific/discrete geographic areas allows callers to determine, and, associate a number with the called geographic location.

MTAS compatible.

Terminal and Personal Mobility - NANP numbers enable networks to identify mobile terminals and mobile subscribers (either those who are traced through the terminal [roaming], or, personal mobility services [PCS]).

MTAS compatible.

Rating/Billing Information (related to distance sensitivity) - For example, in the US every geographic NANP number is associated with a specific rate center. Rate centers provide geographic location information which is used by the network's billing systems to derive the distance between the calling and called party that is used in calculating the cost of a call.

MTAS compatible.

Account Information - The NANP number is widely used by network operators to identify customers with their accounts. Once identified by the NANP number, customer account information such as equipment installed, discount plans, credit rating, etc. information is available.

MTAS compatible.

Routing Information (digit analysis, trunk group selection) - The network utilizes the dialed NANP number to determine how to route each call. Digit analysis of the NANP number is performed at each switching node in a call's path to determine the outgoing trunk group on which to route the call towards its final destination.

MTAS compatible.

Limited Service Provider/Network Identification - Within the 10 digit geographic NANP number, service provider/network identification is achieved through the assignment of a number to a customer from a specific service provider's pool of numbers (e.g. NXX codes in geographic NPA's, etc.) Calls to each customer are automatically routed to them via their service provider's network. The calling customer is provided with no control over either the transit or a terminating network by the NANP number.

MTAS compatible.

In non-geographic applications, NPA 456 was allocated to allow for both transit and terminating network selection on inbound international calls based solely on NANP digit analysis in the originating foreign country. This allocation was made specifically to overcome service provider/network identification shortcomings in the NANP.

MTAS compatible.

Internal Network Routing (0/1XX - NPA's) - Codes in the 0/1 XX range are not currently assignable as NPA codes in theNANP because the 0 and 1 are currently being used as prefixes. As a result of this current restriction, codes in the 0/1 XX format are being used extensively in the network to provide internal routing functionality (e.g. test codes for network maintenance, special routing codes for operator services, intra-network routing, etc.).

MTAS compatible.

3.2 Additional Functions - The current NANP was designed prior to the advent of new telecommunications network(s) needs, such as competition, mobility, portability, enhanced services, etc. These emerging needs are being accommodated by the existing NANP but not always in a graceful, effective, or efficient manner.

Some examples of the above include:

-carrier/service provider - identification/selection is achieved via an NANP adjunct dialing arrangement (equal access/CIC, etc.) which is neither dialable nor functional from outside the "home" country. Specifically, CIC's assigned to U.S. carriers are not functional in Canada, let alone in non-NANP countries. Therefore, the critical functionality provided by CIC's in the U.S.A. is not available elsewhere, because it is housed outside the NANP number.

MTAS neutral.

-the unceasing need to allocate CIC resources to achieve network/carrier identification is an indication of the need for this information by the network and its operators. Information (carrier identification) which is not readily derivable from the existing NANP numbers is therefore being provided ever increasingly through the use of CIC's.

MTAS neutral.

-a number of existing or proposed scenarios require one NANP number for dialing and another one for routing. Among such scenarios are some number portability models, wireless roaming, and a number of wireline applications such as RCF, toll-free (800), memory call, etc.

MTAS neutral.

-the method used to implement "Services" portability (800 today, 500 tomorrow?) destroys the ability of foreign administrations (including NANP Caribbean countries) to select the correct destination country for international routing purposes.

MTAS neutral.

-the trend toward international competition and global service offerings is not well accounted for in the NANP.

MTAS Neutral.

-the ongoing need to have "rate center" based numbering assignments (i.e. NXX/rate center) to satisfy billing and accounting needs is causing excelerated depletion of NANP resources in areas where local competition is being implemented.

MTAS compatible.

3.3 Future Functions - The future NANP must take into account the above and provide solutions where feasible. Some functions which may need to be supported by tomorrow's NANP include the following:

Terminal Identification - A NANP number uniquely identifies the network service access point/interface for every PSTN terminal in terms of identifying the local switch and the specific switch facilities associated with that terminal.

MTAS compatible.

Personal Identification - When a NANP number is used for personal identification, it uniquely identifies an individual/person. Call delivery/routing is controlled by a service profile management capability which directs/routes the calls to a termination point (typically identified by another NANP number) chosen by the called party. SAC 500 is currently available for this type of application.

MTAS compatible.

Service Identification - Service identification using NANP numbers is the association between a number and a service. An example is that calls to 800 numbers are "toll-free" to the calling party.

MTAS compatible.

Geographic Significance - For example, the assignment of NPA codes to a specific/discrete geographic areas allows callers to determine, and, associate a number with the called geographic location.

MTAS compatible.

Terminal and Personal Mobility - NANP numbers enable networks to identify mobile terminals and mobile subscribers (either those who are traced through the terminal [roaming], or, personal mobility services [PCS]).

MTAS compatible.

Rating/Billing Information (related to distance sensitivity) - For example, in the US every geographic NANP number is associated with a specific rate center. Rate centers provide geographic location information which is used by the network's billing systems to derive the distance between the calling and called party that is used in calculating the cost of a call.

MTAS compatible.

Account Information - The NANP number is widely used by network operators to identify customers with their accounts. Once identified by the NANP number, customer account information such as equipment installed, discount plans, credit rating, etc. information is available.

MTAS compatible.

Routing Information (digit analysis, trunk group selection) - The network utilizes the dialed NANP number to determine how to route each call. Digit analysis of the NANP number is performed at switching node in a call's path to determine the outgoing trunk group on which to route the call towards its final destination.

MTAS compatible.

International Inbound Routing Information - The international network (i.e., Internatioanl Switching Centers - ISCs) utilizes the dialed NANP number, preceeded by the country code (1) to select the route for internatioanl traffic inbound into the NANP serving area. The NANP number should provide sufficient information to ensure that international originated calls can be routed directly to each sovereign entity/country within the NANP serving area.

MTAS compatible.

Number Portability - The expanded NANP must support number portability.

MTAS compatible.

Roaming/Mobility - The expanded NANP must support roaming and mobility
functions.

MTAS compatible.

Inter-Country Routing/Services Requirements - Inter-country (intra-NANP and international) services may require the presence of specific information within NANP numbers to enable the direct routing required to support these services, and/or, to ensure compliance with national regulatory requirements for international traffic.

MTAS compatible.

Geographic Service Requirements - The NANP must continue to provide the functions required to support geographic services. Geographic services are generic and basically apply to POTS.

MTAS compatible.

Non-Geographic Service Requirements - Non-geographic services numbering may generically be defined as any service/addressing plan that is not geographically based. However, the services supported by non-geographic numbering are unique today, and undefined for tomorrow. The future NANP must provide the functionality to support both existing and undefined new non-geographic services.

MTAS compatible.

NOTE: The non standard use of NANP or NANP formatted resources, may be seriously impacted by NANP expansion options. For example, internal network routing using 0/1 XX formatted NPA codes would not be possible if the plan called for the 0/1 XX NPA code option.

MTAS compatible.


4.0 ASSESSMENT CRITERIA - This section describes the criteria which have been established by the industry to assess the various NANP expansion options. It is recognized that due to the timeframes involved, and, the resulting need to rely on assumptions regarding the future of North American numbering and addressing, that the assessment process must focus on the relative merits of one plan versus another. It is also recognized that certain expansion options may fail to satisfy even the most basic criteria and therefore should/could be eliminated from further consideration as quickly as possible.

Finally, since most expansion options include the potential for a phased approach, assessment must take into account the merits of each phase as well as the total expansion package.

Those options reviewed and eliminated by the Workshop are listed in Appendices C & D. Appendix C includes those options listed in Section 5 which were reviewed in detail but not selected. Appendix D lists those options reviewed but not included elsewhere in the document since they did not meet even the most basic assessment criteria in Section 4. The rationale for eliminating options is included in the appropriate appendix.

4.1 Human Factors Needs - Any expansion plan will have some impact on the users ( e.g., the general public) of the numbering plan. Therefore, the expansion plan should be examined based on the degree of impact from the perspective of the general public. The following four areas should be examined to understand this impact:

4.1.1 Degree of Stability - Any expansion of the NANP capacity will affect all end users. The expansion plan, including any transitional steps, should minimize the frequency and extent of number changes required to implement the new plan ( e.g., maintaining the basic numbering structure where the geographic NPA code represents the geographic area associated with the destination address of a call and the last digits represent the subscriber station. These numbering fields should not be moved, inverted or reversed). Moreover,with the rapid increase in demand for numbers the resulting increase in new NPAs, it shoud not be assumed that the next expansion plan will or should be implemented when the NANP is at or nearing exhaust of the current NPA supply. When evaluating NANP expansion options, the benefits of implementing a plan sooner, should be considered.

MTAS superior to alternative options.

4.1.2 Easy to Understand - Acceptance by the general public of any new numbering plan starts with a complete understanding of what is changing in the numbering plan and why it is changing. As an objective, an expansion plan, including any required transitional steps, should be relatively simple, without multiple, complex activities that may be difficult to explain to the general public. Any changes should be applied consistently, uniformly and ubiquitously to all end users. A plan that varies across the geographic area served by the NANP may result in confusion, disruption and possible resistance to its implementation.

4.1.3 Easy to Use - Of primary importance is the requirement that any new numbering plan be easy to use. This will likely be perceived by the public in terms of how the new numbering plan differs from the existing NANP format. The expansion plan should attempt to minimize the number of new digits required, while balancing this need with the requirement for additional functionality and flexibility that will be necessary in the numbering plan in the future. A logical, transition plan, will be necessary with any new expansion alternative. This transition plan must ensure easy access to the public network without burdening the end user with numerous, cumbersome and on-going numbering plan changes that lead to frustration and confusion.

MTAS superior to alternative options.

4.1.4 Clarity of Purpose - The NANP number conveys to the end user certain information, including in some cases, the service associated with the number . For example, there are the geographic "POTS" numbers, toll free services (e.g., 800 and 888), pay-per call services (e.g., 900), 911 for emergency services and new services (e.g., 500 for personal communications). The expansion plan should retain the same type of number recognition for these types of services.

MTAS superior to alternative options.

4.1.5 Future of "Dialing" - In assessing NANP expansion alternatives, the "dialing" procedures used currently, and for the foreseeable future, by the North American telecommunications users must be considered from a human factors perspective. The expanded NANP format must accommodate, in a "user friendly manner", all the dialing methods in place at the time of its implementation. In the context of this section, "dialing" includes the method used (manual or automatic), and the digits input, by the user to indicate to the telecommunications network the NANP destination address for which a call is intended [Reference Annex B]. There are two main categories of dialing methods - manual and automatic.

Manual Dialing - This method of dialing requires that the user physically inputs, every time a call is originated, every digit of the destination address to the telecommunications network. Typically, this is via a dial pulse (DP) or multifrequency (MF) terminal using a rotary dial or a touch-tone keypad.

Despite the availability and deployment of new technologies in the area of accessing the telecommunications network, manual dialing will be in use for the foreseeable future. The human factors aspects of remembering and manually dialing an expanded set of digits for each call are of particular interest. Consequently, manual dialing must be considered when assessing the viability of an NANP expansion plan.

Automatic Dialing - This method of dialing requires an "intelligent" terminal interfacing with the telecommunications network to input the digits of the destination address. The terminal is programmed to recognize, by one of several methods, what destination address is desired by the calling party. The programming can be simple as "speed dialing" where the user manually inputs an abbreviated code (usually 1-2 digits) identifying a destination address and the terminal matches that code to the full preprogrammed NANP destination address and performs the "dialing" function; to computer generated broadcast addressing where a list of addresses can be used to generate ("dial") the same message to multiple destinations in a relatively brief period of time. All forms of Automatic dialing requires the calling party to input the full number at least one time in a manual fashion.

The key point with regard to automatic dialing is that, depending on the sophistication of the "intelligent" terminal, longer numbers can be more readily and easily input by the user than with the manual dialing process. The ability to remember and dial longer digit streams is much more feasible with the programming of a "smart" terminal than it is by depending on the memory and manual dexterity of the user.

Many automatic dialing methods have been discussed recently. Some, such as machine generated and voice generated, are already available in some networks. Others, such as ESP generated, are yet to be developed.

Since the main attributes of all the automatic dialing methods are programmable network access and the potential for easily using ("memorizing") longer NANP numbers, there is no advantage to discussing each of the methods. It should be sufficient to say that the main difference between the various automatic dialing methods is the ease by which longer digit streams and more digits can be handled and processed. The less sophisticated speed calling services are comparatively limited in the quantity and length of the numbers that can be programmed in comparison to the more sophisticated computer or voice generated dialing methods.

MTAS Compatible

4.2 Impact on Call Processing and Network Operations - The current 10 digit format of the NANP is inherent in all phases of call processing and, therefore, embedded in the functions provided in all network elements. The major areas/elements potentially impacted by a change in the NANP format include the digit analysis and translation required for call routing, the signaling associated with call set-up and the use of special features, the functions supported by operations support systems (OSSs), the services offered by operator services systems, the recording and billing necessary for preparation and the rendering of customer charges, and the provision of emergency services (E911).

4.2.1 Digit Analysis and Translations - Digit anlaysis and translations are required for call routing. Within the current 10 digit format of the NANP three digit anlaysis is typically performed on all calls and is sufficient to identify the NPA of a 10 digit dialed call or the NXX of a 7 digit dialed call. This three digit analysis can therefore often be used to determine the interLATA/intraLATA nature of the call, and whether the call must be routed to the presubscribed carrier. Also, three digit anlaysis of a seven digit dialed call will, in a non-portable environment, identify the end office to which the call must be terminated. In those situations in which three digit analysis is not adequate to effect proper call routing, six digit analysis (NPA-NXX) is performed to further identify the disposition of the call.

The numbering plan will continue to play a key role in call routing regardless of the plan format. For example, expansion of the NANP to accommodate an additional digit in either or both the NPA or CO code fileds will directly impact the digita analysis and translation processes. Digit analysis to identify either the NPA or the CO code would require four digits, and those instances where analysis of both NPA and CO code are required would demand analysis of eight digits (assuming an additional digit is added to both the NPA and CO code). Moreover, translation/routing tables would need to be expanded with the possible resultant need for additional switch memory.

It should be recognized that proposals which do not add digits to the existing 10 digit structure, but add capacity to the numbering plan through the use of presently restricted digits (e.g., the use of "0" or "1" in the D digit) would also impact switch hardware and software associated with digit analysis and translation. Specifically, the use of "0" or "1" in the A or D digit is currently prohibited in most network hardware and software, and their inclusion in valid dialed numbers would require network modifications. The extent of those modifications would have to be determined.

Examples of current uses of 0/1XX codes ("A" and "D" digit) are as follows:

"NPA-like" codes (e.g. 100, 101 etc.) are used as test codes; these codes can only be dialed by technicians from test positions;

"Pseudo NPA" codes (0/1XX codes) are used to route traffic on dedicated trunk groups on a switch to switch basis where the actual NPA is deleted and a pseudo NPA is inserted for routing purposes. This may occur on an intranetwork basis or over the public network.

Central office codes in the 0/1XXX format are used as billing numbers for both INWATS and OUTWATS lines. These numbers are usually in the format of 00X-XXXX for INWATS and 01X-XXXX for OUTWATS.

Pseudo numbers in the format 0XX-XXXX are sometimes assigned to ACD (auto call distribution) groups to conserve "real" numbers. These numbers are always associated with a "real" lead number and are never directly dialed by subscribers.

0/1XX codes are used in the Caribbean for a variety of purposes including, USA direct dialing, international inbound 800, and some OSPS services.

Additional network capabilities required for call routing associated with an expanded NANP should be balanced against possible advantages or functionality that a given expansion plan might offer. For example, a format which would include a national desitnation code (NDC) would require additional analysis and translation, but could afford recognition of a specific network associated with the call.

MTAS supported.

4.2.1.1Digit Analysis on Inbound International Calls - The digit analysis required with an expanded NANP could also impact call processing associated with inbound international calls. Specifically, for those numbering resources assigned today to carriers on an NXX basis -- e.g., the 500 SAC and the 456 code -- call processing in foreign networks can use (7) digit analysis to identify the service provider. Consequently, the call ccan be routed ove that provider's network rather than routed on a proportionate basis. An expanded NANP that would, for example, include a 4 digit area code or a 4 digit central office code, (or both), and would continue to assign some resources to entities on a central office code basis, would clearly require additional analysis and translation capabilities in foreign networks to preserve such carrier specific routing capabilities.

Moreover, any change (i.e., more than 7 digits) in the analysis recommended within foreign networks on calls inbound to the NANP would require modification to existing international standards and would, therefore, require activity within international (ITU-T) standards committees.

4.2.2 Signaling -

4.2.2.1 SS7 Standards Impact

A preliminary analysis of SS7 ISUP signaling protocol shows that ANSI
T1.113 formats for most parameters would not be impacted, as the current
defined length is sufficient to incorporate up to 16 digits, with one
identified exception. The parameters examined included called party
number, calling party number, charge number, generic address,
jurisdiction information, original call number, and redirecting number
parameter. All parameters have a defined length that allows up to 16
digits with the exception of the jurisdiction information parameter (JIP).
The JIP as currently defined can accommodate up to 6 digits. If the NPA
or NXX were expanded, or an additional digit were inserted prior to the
NPA, the length of the JIP would have to be increased.
A preliminary analysis of the ANSI T1.112 - SCCP protocol standards
indicates that the format of the Global Title is variable length. The
Global Title contains Global Title Address Information. There is no
apparent digits limit. The same appears to be true of ANSI TCAP T1.114
standards. The digit length is variable and a Number of Digits field
exists to be encoded to indicate the number of digits in the digits field.
 
MTAS compatible.
 
4.2.2.2 SS7 Applications Impact
 
Applications that have been developed to utilize the SS7 signaling protocol will need to be examined to determine the implementation of the
standard and whether or not the application software will need to be
modified. Applications that only include 6 digits in the Global Title
Address, for example, will need to be modified to include additional
digits if the NPA and NXX are expanded. Applications that currently
include or rely on 10 digits in the GTA may need to include additional
digits if the number is expanded. Applications that have the Number of
Digits field in the TCAP message set to 10 will have to be modified
to define the new quantity of digits that will be in the Digits field.
It is not clear whether implementations of ISUP will be impacted (with
the exception of the JIP) because both the T1.113 ISUP standard and the
Bellcore generic requirements documentation (footnote) support
parameter lengths that can accommodate 16 digits.
 
MTAS compatible.
 
Footnote: The issue of Bellcore GR 317 reviewed for this analysis, however, does diverge fom the T1S1.3 Standard on one parameter and that
is the Charge Number Parameter. The Bellcore documentation provides a
parameter length that would only support 10 digits.
 
MTAS incompatible.

4.2.3 Recording and Rating - Call detail recording, performed in network switches and operator systems, is currently designed to accommodate the current 10 digit number format. In addition, downstream rating processes, which collect the call detail and develop the charge associated with the call are also built upon the current number structure. Specifically, call rating is typically performed by the recognition of the location associated with central office codes (NPA-NXX) of the calling and called number, the computation of call distance and time, and the assoication of the related charge. Location infomation assoicated with NPA-NXX is provided in industry documention. The addition of one or two digits to the existing structure will directly impact these systems and the supporting industry documentation. The addition of one or two digits to the existing structure, and -- perhaps to a lesser degree -- the use of formerly restricted digits (e.g., "0" or "1" in the D digit) will directly impact these systems and the supporting industry documentation.

MTAS compatible

4.2.4 Operations Support Systems - OSSs support a multitude of functions including, for example, repair and provisioning. These areas, along with almost all other areas which involve the use of support systems, use the existing numbering plan for identification of the customer and/or a network switch. Clearly, a change in the structure of the NANP will require modification to allow the use of an expanded NANP number. These modifications may be extensive as NANP numbers are likely to be embedded throughout the software associated with these systems.

MTAS compatible.

4.2.5 Operator Service Systems - Operator Service Systems combine many of the functions described above. That is, these systems perform digit analysis and translation to support call completion on operator handled calls. Further, signaling capabilities are inherent to these systems, not only for call completion, but also for processing associated with alternate billed calls, which are routed through the operator systems. Finally, operator systems may perform recording and can provide real time rating information to callers. Accordingly, because all these functions are impacted with a change in the structure of the NANP, operator systems will require significant modification.

MTAS compatible.

4.2.6 Emergency Systems - E911 systems direct emergency calls to a central location (the Public Safety Answering Point or PSAP) and identify the location of the calling party. This identification is typically resident in a database which lists the location for the calling number. Significant changes within this database and the mechanisms used to obtain information from the database would be required with any expansion of the NANP structure.

MTAS compatible.

4.3 Life Expectancy of Expanded NANP - A primary goal of any expansion plan is to maximize the life of the expanded numbering resource. This is a function of the quantity of numbers created and the rate of consumption of those numbers. Any expansion plan should maximize the quantity of numbers created while balancing it against the rate of consumption and minimizing its impact on the public switch network, dialing considerations, other number resources and the general public.

Annex E provides the details of the estimated exhaust date of the NANP in its current format including the assumptions used in making this determination. Each expansion option that is selected for evaluation will require the determination of the estimated exhaust date and its associated assumptions. Estimated exhaust dates will be based on assumptions with regard to the capacity and usage of the numbering resource. It may be necessary to evaluate each scenario against multiple common sets of assumptions.

MTAS increases functionality of existing addresses.

4.4 Numbering Resource Utilization/Efficiency - The expansion plan must support the efficient assignment and utilization of numbers in order to increase the life expectancy of the new numbering plan. The expanded NANP must also support emerging methods for better utilizing NANP resources (e.g. number portability, number pooling, etc.).

Several potential mechanisms for better utilizing NANP resources in the future have been considered by the industry (Reference ICCF Report on Rating and Routing In A Competitive Local Environment ICCF96-1220-016). These proposals include the designation of a rate center or a central office switch, not by an NPA-NXX, by a more granular identification such as 1000s block. Reducing the number of rate centers or allowing inconsistent rate centers are other potential alternatives that could lower the demand for CO/NXX code assignments. Another option could be number pooling which would require the modification of existing number assignment practices so that numbers would be assigned to a geographic area (rate center) and those numbers would be available to all service providers who serve that area. Number pooling should be considered as the number assignment process to be used when permanent data base solution for service provider portability is available. The expansion plan being considered should have the flexibility to accommodate these types of equivalent mechanisms to achieve better NANP resource utilization.

MTAS increases functionality of existing addresses.

4.5 Accommodating Future Network Requirements - Today's PSTN is comprised of the separate networks of multiple network operators/providers supporting unique services. In addition, there are a number of services such as data, packet and voice which are provided over these networks. Therefore, the continuing growth of individual networks, the services provided and the potential merging of voice/data/video networks will require a numbering plan that accommodates all such future network and service requirements.

MTAS increases functionality of existing addresses.

4.6 Requirements Between Countries Served By The NANP - The plan should continue to allow for identification of and ubiquitous connectivity between countries served by the NANP. The plan must also be flexible enough to adapt to the possibility for the expansion in the number of countries served by the NANP and the possibility of segregating the use of the resource between networks, network providers and/or service providers within these countries.

MTAS compatible

4.7 Consistency With Public Policy - An expansion plan should not interfere with the public policy goals and requirements of all of the countries served by the NANP. In order to support a competitive market structure it is essential that the expansion alternative, in and of itself, introduces no discrimination between or among service providers and the services that they offer.

MTAS compatible

4.8 Uniform Availability of Numbers - The expansion plan must provide additional numbering capacity which can be used by all segments of industry. The plan should not disadvantage one industry segment over another. In addition, any expansion plan needs to consider national, intra NANP and international inbound calling requirements.

MTAS compatible

4.9 Additional Digits - Each digit added to the ten-digit NANP number format will add additional capacity and may add additional functionality. The capacity and functionality gained is subject to a cost/benefit analysis. The expanded plan must continue to support existing functions.

MTAS compatible

4.10 Evolution/Transition - With the development and implementation of a new, expanded numbering plan it is necessary to understand (1) how the transition will take place from the existing numbering plan to the new plan, and (2) the manner in which possible future expansion from the new plan to yet a further expansion might be accommodated. In general, the transition plan should be relatively simple, without multiple complex activities which add layers of difficulty that the user public may not understand. Moreover, and most important, the transition plan must allow the new numbering structure to be introduced selectively, without the need for a flash cut to the new numbering format for all existing subscribers, i.e., any transition plan may need to include a permissive dialing period.

Typically, this transition is accommodated by allocating specific digits or digit strings within the numbering plan which are set aside and unavailable for assignment during the "normal" life of the plan, and only introduced with the implementation of the new, expanded numbering arrangement. The use of these unique digits allows network elements (e.g. network switches) to easily recognize that the new numbering format is being dialed.

Indeed, within the current structure of the NANP, area codes in the "N9X" format have been designated for this use. That is, it has been suggested that numbers within the expanded plan be initially assigned with "N9X" as the first three digits, allowing the expanded numbers to be easlily recognized and, therefore, introduced and used along with the continued use of numbers in the exisiting format. Although unlikely, it is possible -- notwithstanding the current allocation of the "N9X" series for expansion -- that transition to the numbering plan ultimately selected might be better accomplished with some digit resource other than "N9X". In any event, it is critical that these resources be identified and reserved early enough in the life cycle of the exisiting numbering plan to ensure that an adequate quantity of appropriate resources are available to effect the required transition.

Similar consideration must be given to a possible future transition from the plan selected to expand the current 10 digit structure to a future, as yet undefined plan which may be necessary at some future time to provide still more numbering resources. Accordingly, specific resources within the new plan should be allocated to accommodate transition for further expansion.

Any numbering plan change generates significant impact. Therefore, it is important to allow sufficient time for the transition to the new plan to enable the public, the network operators, service providers and vendors to appropriately plan for its implementation. This involves customer education, development of network specifications and requirements and scheduling of appropriate testing/trials. Accordingly, whatever future expansion plan is agreed to for the new North American Numbering Plan (NANP), it is important to:

1) Allocate a series of codes to allow for transition to the new plan
2) Agree to a schedule for the implementation of the new plan
3) Allow sufficient time for the transition
 
MTAS can be readily implemented in compatible stages.

4.11 Administration - Administration of the 10-digit NANP number has been based primarily on the elements in the number (e.g., NPA or area code, NXX or central office code and XXXX or line number). Industry assignment guidelines have been developed to administer these resources. Any future numbering plan should continue to allow for this ??? ease of administration.

MTAS compatible.


Remainder of the INC-NANP Expansion Report concerns options submitted to INC to increase the capacity of the NANP. There are two categories of options: those that do not require expanding the ten-digit NANP format and those that do.

 

Full copies of the draft of the INC-NANP Expansion Report describing these options are obtainable from

Frank Colaco, INC General Secretary

fcolaco@notes.cc.bellcore.com


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