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Maintaining general unreachability


By Scott Bradner


I have a cell phone and you do not have the number, and I want to keep it that way.  But, if some of the good people in the cellular phone industry have their way I may soon have to pay for the privilege of privacy in this case, just like I have to in other dealings with the phone world. 


New reports surfaced the end of May that the Cellular Telecommunications and Internet Association  (CTIA) ( was developing a directory that would include listings for about 75% of the 164,424,519 million US cell phones. (The number comes from the CTIA web site and was current on May 31 at 3pm EDT)  Steve Largent, the president of CTIA, was quoted in the press as having said: "this system will provide consumers an opportunity to opt in, if they choose."  Pardon me for scoffing.  The chance of the CTIA directory getting more than 120 million people to individually authorize the CTIA to include their cell phone number in the CTIA directory is vanishing small. Mr. Largent is being disingenuous at best.  Almost all of the authorizations that Mr. Largent seems to be referring to are buried in the very fine print deep inside the contracts we have to sign (and are not permitted to modify) when we get cell phone services.  Hardly the individual "opt in" that Mr. Largent implies.  The phone companies have dealt with this sort of thing before.  They have a simple answer: make the customer pay.  It costs me $1.21 per month to not have the number of my fax machine  listed in the printed Verizon white pages directory.  It would cost an additional fee to have the number not be handed out to people who call directory information.


Since the CTIA is not likely creating this directory out of the goodness of their heart, they must have a business model in mind.  Since this is a major project one would think that there would be information about it on the CTIA web site but the only mention I can find is in an article titled "wireless directory brings up privacy issues" on the "daily news" page for May 20th.  This article mentions that U.S. Representative Joseph R. Pitts (R-PA) introduced a bill to block including cell numbers for people who have not actually authorized it and mentions that Verizon said they would not cooperate (which means I do not have to worry about the threat for myself - yet). One business model would be to extort money from people who did not want to be included.  Press reports say that the CTIA claims this will not happen but I have not found where the CTIA directly says that.  I wonder what the business model is.


How the phone industry deals with this directory may foretell what will happen with enum.   Enum is an IETF technology that will be used to map phone numbers into Internet URIs.  (See  There are a lot of potential uses for enum, see for more information. (   This is another case where customer opt-in will be vital for preserving customer privacy.  It would be nice if the "opt-in" actually meant it.  We will see if CTIA actually can understand the concept.


disclaimer:  developing and understating concepts is the raison d'etre for a place like Harvard but the above observation is my own