[LINK] How does LinkedIn know my contacts?

[Paul Brooks]

On 11/02/2013 4:07 PM, Jan Whitaker wrote:
> I think it's interesting that this question in conjunction with an 
> increase in spoofing and spam came up in our computer club last week 
> and I advised everyone to stop giving their contacts away to 3rd 
> party sites (on top of the other advice of use Bcc when possible).

FWIW, the Viber VoIP app that seems to be so popular at the moment also requires a
subscriber to upload their phone directory to work.
While the signup blurb reads 'no registration required, no waiting for invitations',
in practice it is your telephone number that is used as your registration, and it
uploads your address book to tag which people in your address book are also using
Viber and can receive a VoIP call by matching telephone numbers. This is a mandatory
part of the installation process.

Now mobile phone directories often merge together details of contacts from several
different contexts, such as LinkedIn, Facebook, Yahoo etc as well as synchronised
entries from a desktop PIM and information entered manually - which means a friend who
also has linked my contact details with my LinkedIn profile for example may have
uploaded my name, home street address, work street address, landline number, mobile
number, employment position, company, company email address, persnal email address etc
etc etc, without me being able to do anything to stop it.
 
It would be interesting to hear how many of your computer club have installed Viber
for cheap calls on their mobile phone.

Paul.