The following text is copyright 1998 by Network World, permission is hearby given for reproduction, as long as attribution is given and this notice is included.

Why we do what we do

By Scott Bradner
Network World, 5/25/98

Massachusetts is running out of phone numbers - again.

Less than a year ago, two new area codes were carved out of the two
area codes that have been serving eastern Massachusetts for years.
We are now told the newly created area codes may run out of
numbers as early as the year 2000.

Massachusetts currently has five area codes. Five area codes could
theoretically support 49,999,995 phone lines. Even if one were to
assume a good penetration of office phones, fax machines, cell
phones and second lines to support teenagers, the ability to support
nearly 50 million phone lines should not be all that confining in a state
whose total population was 6,016,425 people in 1990.

Now the phone companies want to add support for 20 million
additional lines. I don't think that many people have suddenly decided
shoveling snow is a fun task and therefore it's time to move to

The basic reason for this clear inefficiency is that the phone number
assignment rules are severely limited by the technology of the phone

If I wanted to start a cellular phone service in an existing area code, I
would go to the phone number assignment authority
(, and if I met the authority's requirements, I would
be assigned a block of phone numbers. The minimum size block of
numbers that can be assigned is 9,999, even if I only have 10

This distribution process can result in inefficient use of the potential
number space. The problem, combined with the demand - The
Boston Globe reports there were 57 requests for phone number
blocks in one of the area codes during the week of May 11 - means
more area codes are on the way.

The Internet used to assign IP addresses in fixed- sized blocks like
this, with block sizes of 256 hosts (class C), 65,000 hosts (class B)
or 17 million hosts (class A). But this system changed a few years
back with the development of classless interdomain routing.

The Internet address assignment organizations - the American
Registry for Internet Numbers (ARIN) serves the Western
Hemisphere and southern Africa - now assign IP addresses in
power-of-two sized blocks. The size of an assignment is based on the
actual size of the organization, backed up by concrete documentation.
(ARIN's Web page is at

The change in assignment procedures has dramatically moved back
the time at which the 'Net will run out of IP addresses and thus, the
time at which a switch to IPv6 will be forced by address exhaustion.
There are other reasons organizations may want to migrate to IPv6,
but it seems that the move won't be forced.

I hope the companies learn how to be more efficient because I'd just
as soon not change my phone numbers. But the problem may cure
itself if the projected Internet takeover of the phone system happens
soon enough.

Disclaimer: Neither ARIN (where I'm a board member) nor Harvard
(where I have an ambiguous title) does anything with phone
numbers except try to remember a few of them.