When Did My Cell Number Get Published?

As I’ve mentioned before, I hate the telephone.  However, I actually have a cell phone anyway, for emergencies and the like.  As my stated goal is to never actually use the thing, I believe I have the cheapest plan in the galaxy – $10 per month.  That only gets me about 20 minutes of talk time, but I use it so rarely that in the 15 months I’ve owned it, I’ve banked over 7 months worth of minutes.

Anyway, only a very few people know the number to this little phone: my wife, our babysitter, and a few neighbourhood friends who in the past we have had to co-ordinate arriving somewhere with.  And it’s not listed anywhere that I know of.  I’ve never entered it as contact info anywhere.  It rings (or at least used to ring) so infrequently that I have at times not recognized my own ring tone.  It’s only when everyone’s looking at me with a “Why aren’t you answering your phone?” expression that I realize it’s mine.

But suddenly all that has changed.  In the last couple of weeks, I’ve received about 20 calls on my cell phone.  One, I answered even though I didn’t recognize the number, because it came from my area code — it was a wrong number.  But all the others are from area codes I don’t even recognize like 310, 510 and 909 (all California).  I’ve answered 3 or 4 of them out of curiosity, and as you’ve already guessed, they are all phone spam.  Recorded messages that I don’t listen to long enough to even learn what they want from me.

So I am intrigued as to why it took the spammers so long to find my number.  If there is some computer somewhere trying every possible phone number and flagging the ones that don’t answer with “this line is not in service,” or a fax or modem signal, and it was  just a matter of churning though all the possibilities?  Let’s do some math: there are about 375 area codes in North America, and let’s say that that the average one uses about half of its available exchanges.  So there are 500 × 375 = 187,500 possible 4-digit extensions.  So we have 187,500 × 10,000 = 1,875,000,000 possible phone numbers on the continent. 

If I set up 10 PCs calling one of these possible numbers each every 10 seconds, it would take me 59½ years to try every one.  If I used 100 computers, 6 years.  1000 computers = 7 months.  Is that what happened?  Is there a phone-spam funded server farm somewhere testing possible phone numbers all the time?