Moving 7D -> 8DThe Problem - Moving Directly from 7D to 8D
Most plans call for a move to longer than 8D dialed numbers first. I believe this would be a bad step. Unless a move to 8D is guaranteed by contract or law, I do not expect any 'temporary' longer numbers to be shortened to 8D. The complete loss of shorter than full length dialing, even with an enforceable guarantee of allowing 8D "in the future" is a burden that I believe should be avoided. The world won't end, but for many people using the telephone will be less pleasant. Therefore I have a hard time supporting any 'temporary' moves to 10D, 11D, or 12D dialing.
Numbering Plans and Dialing Plans
There is a difference between numbering and dialing. Numbering plans are how numbers are assigned, dialing plans are how subscribers reach those numbers. The plans go hand in hand especially in a transition period as the dialing plan needs to support permissive dialing of the old and new numbers. Certain ranges set aside in the numbering plan can aid in uniquely identifying in the dialing plan what number is desired. Those reserved numbering ranges provide 'gaps' in the dialing pattern that can be exploited by a transition dialing plan.
7D Dialing Plan Gap
7D numbers currently start with "a digit not 0 or 1". The remaining six digits can be any digit. That leaves little room for exploitation. The only way to distinguish an old 7D number from a new 8D number during permissive would be to have the new 8D number start with a zero or one. That leads to a problem: Currently 0 and 1 are in use with 11D and other dialing strings. In order to use one of those digits, we would need to reclaim its use.
As 1+ dialing is more common that 0+ dialing, the choice would be 0. This is a tough decision to make as dialing 0+ for Operator Assistance is an old part of the current dialing plan. But I believe that it can be done IF we give subscribers something in exchange. A direct move to 8D numbers are that exchange. The a staged transition will be needed, as one cannot permissively have 0+10D and 0+7D numbers. So the actual transition from 7D to 8D will have to take place AFTER 0+10D is replaced.
Clearing the Zero
Zero is currently used for the following:
It would be best to do this change in conjunction with expanding the NANP to a full 12D number from the current full 10D number. Not only could the publicity be shared, but the full 12D pattern of NPAX-dnxx-xxxx (with the new NPA being four digits, and 'd' initially being zero) would be reinforced.
Keeping Operator Assisted|
While not used as widely as it once was, I do not wish to destroy operator assisted dialing. "0" and "00" will continue reach local and long distance operators, I suggest that the "0"+10D dialing be replaced by "001"+10D (which will eventually be "001"+12D). This will require adding a timeout to "00" dialing. While it would be possible to move to a "00"+10D/12D system, foreign visitors may find that confusing. For most of them, 00+1 is a call to the NANP and 00+n is an international call to some other area in the world. That confusion is unnecessary.
In addition, with the timeout added to "00", it would be possible to allow "00"+ as "Sent Paid International" along side the current "011"+ access. This would help foreign travelers in their dialing and make the NANP dialing system more unified with the rest of the world. "01"+ would remain as "Operator Assisted International".
Overlay Area Considerations
Overlays are not permitted to have 7D dialing (except by waivers that are not intended to be permanent). A direct 7D to 8D process would not be possible in overlay areas. However overlay areas are a big argument for having 8D dialing. A numbering/dialing scheme will need to be specifically invented for each overlay area to allow for 10D -> 8D and yet still fit in with the national 12D plan.
Of course, with all the discussion of HOW to migrate 7D to 8D, the first question needs to be "Should We?". Initially we will have 8D numbers that ALL start with zero, which is redundant in areas where 7D numbers are enough to last. It may be several years until an 8D number that doesn't start "0" is assigned.
I compare this to the current 10D overlay system. 10D numbering is required when the first new exchange in an overlay is assigned, but it may be years until that overlay is 'visible' to the general public. In these 10D overlays, the first three digits of the number are redundant initially, and even after the overlay becomes well known those three digits serve a purpose that could be served by one digit.
The cost of having a uniform numbering system within each country requires that the entire country uses the same length local number. The 'cost' of dialing the 'redundant' zero is smaller than moving to 10D, 1+10D, 12D or 1+12D dialing. I believe the benefit is worth that cost.
[Introduction] - [Moving 7D -> 8D] - [12D Plan] - [Transition] - [Complete Review]