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Non-numeric numbers


By Scott Bradner


On June 6th a federal appeals court in Washington DC decided to let the FCC require that cell phone carriers let their customers keep their phone numbers when switching between cell phone providers.  This means that cell phone customers will soon have about the same rights to keep their numbers as people with wired phones have had for a few years and operators of "800" lines have had for 10 years.  Basically, they will have the right to treat their phone number as if it was not a number.


The court's decision ( hinged on a legal technicality and the definition of the word "necessary," and could, in theory, still be appealed.  It is also possible that the US Congress could be persuaded, by dint of argument or donation, to overturn the decision.  But as of now it looks like the FCC rule will continue to push for an end of November implementation date.


The ability to keep a phone number while changing providers is known as number portability.  (See IETF RFC 3482 ( for a good explanation on how telephone number portability works around the world.)   If you look at your phone bill you will see a number portability fee (mine was 23 cents last month) that the phone companies charge for the service even though you may not be taking advantage of it.  It should be noted that the ultimate types of number portability, keeping the same phone number when changing from wired to wireless or when moving across country, are not included in the current FCC plans.


Once upon a time there was real structure in all of a phone number.  You could tell the country, region of a country, city and sometimes, part of a city by parsing the number.  This was because the number was used to route the phone call.  But number portability removes most of that structure.  You can still determine the country and, for now, the region in the country.  But the number is no longer used to actually route the phone call.  The number you dial (funny that it's still called "dialing") is looked up in a database to get another number that is used to actually route the call.  I.e., the number you dial is no longer a number; it is actually functioning as a name and is looked up, just like you would up a name in a phone book, to get the real routing number.


Another place that the number-as-name change can be seen is in the IETF "enum" protocol.  ( With enum a phone number is looked up in the domain name system, just like, to get contact information.  Not just phone contact information, but also potentially web page, postal and email addresses, and voicemail.  Some people have privacy concerns with enum and the Center for Democracy and Technology (CDT) has put together a white paper on the issues.

( I'm not sure I buy some of the worry, considering the ability of Google to find information based on phone numbers, but it is a good policy debate.


Now the real question arises: now that your phone number can be a name, do you want it to be your name?


disclaimer:  I think that Harvard would not have the same punch if it were known as 1 617 495 1000 but the University has not expressed a view that I know of.