Long Term Numbering Plan

3. Inadequacy of Present Remedies

4. LONG TERM NUMBERING PLAN
The Industry Numbering Committee (INC) of the Alliance for Telecommunications Industry Solutions (ATIS) is presently considering several expansion options described in their NANP Expansion Report and denoted the Long Term Numbering Plan (LTNP). The options are to be within the 10-character NANP framework, but not to exceed 12 characters so as to remain within the accepted international connectivity recommendation.

Area Coding Modification
To expand the number of available addresses yet remain within the NANP framework will require that the 0 or 1 limitations on the <a> or <d> character be lifted, but this modification will impact directly on the access protocol for long distance calling. Essentially this option will result in the scrapping of the NANP as presently constituted rather than its modification.

Additional Digit Options
Alternatively, placing an additional digit at a specific position in the telephone address will increase the available addresses throughout the NANP service area. Essentially a new bound-group arrangement would be used requiring a new mnemonic, but this arrangement would be fixed for all addresses and therefore so would the mnemonic. Some dozen or so LTNP options are presently being considered. These can be categorized as follows:

Increase line number digits from four to five:
n (abc) def-ghijk
This is the most straight-forward and least disruptive approach, but the least compatible with the present addressing protocol.

Increase COX digits from three to four:
n (abc) defg-hijk
The <d> character would still be restricted to digits between 2 and 9 for NANP compatibility. Although several COXs can be housed at the same installation, adding COXs will probably require considerable physical restructuring.

Increase area code digits from three to four:
n (abcd) efg-hijk
Although the <a> character would still be restricted to digits between 2 and 9 the number of NPAs would increase significantly, permitting already sub-divided NPAs to be further fragmented. The result would be a multitude of miniscule NPAs so small that most calls would be long distance, essentially resulting in full 12-character addressing.

Destination Coding
Introduce a National Destination Code (NDC) to distinguish between countries served by the NANP :
nxx (abc) def-ghij
The NANP service area covers several countries. The NDC would be used when calling from one country to another in the NANP service area. There are several variations on NDC, depending on the number of digits in the NDC, and the position of the NDC in the address.

Address Expansion
All of these LTNP options involve lengthening telephone addresses rather than increasing the functionality of the addresses already in service. Essentially the LTNP will increase the number of possible addresses ten-fold while less than five percent of the presently available 6.4 billion addresses are even in service. The LTNP options constitute no more than a brute-force approach.

Implementation of LTNP will be somewhat troublesome inasmuch as LTNP is not particularly compatible with present PSTN addressing. A transition period will be difficult to arrange because the PSTN switches will not be able to recognize a priori whether the address dialed had one greater or one fewer digit, essentially the same problem found with Fax Routing.

The public resentment arising because all telephone addresses in the whole NANP service area will have to be changed will be matched by the public resentment over additional digits to be remembered and dialed, as well at the realization that the incident of calls misdialed will increase with the number of digits dialed. That the present LTNP options cannot be readily implemented may be their only saving grace.
5. MULTIFUNCTIONAL ADDRESSING SYSTEM