Today I got an interesting screen on twitter:
Now stop for a second and think about this. Twitter won’t reveal my phone number, but they will let people search for me by my phone number.
So if I just search for all permutations of phone numbers for a given NPA (area code) and NXX (the first three digits of a phone number in the USA), I can make a list of twitter users in a given geographic area or at a specific business. NPA is often a geographically large area, but a given NPA/NXX pair can be very small — as small as a single company or small town.
Obviously you’d get caught trying to search for a bajillion contacts at once, but if I opened ~50 twitter accounts and added 10-20 numbers to each account per day, I could do 500-1000 lookups and cover a given NPA/NXX pair within a week or so.