On Sun, 16 Feb 2014 06:19:21 +0000 (UTC), Geoffrey S. Mendelson commented
on:

Unlock codes are specific to the phone. If one worked for all phones, do
you think people would go to such trouble to get one?

They are actually specific not only to the phone, but to the service
provider. So if you bought the phone from T-Mobile, it would have a different
code than the same phone bought from AT&T.

More particularly, an unlock code is specific to a given handset's IMEI.
The manufacturers leave it, in part, to the service providers to determine
to whom and under what circumstances to reveal the unlock code and
directions for its use. But "service provider" is not used so restrictively
as to mean cellular operators only, for, as you say,

Some phones can be unlocked by buying the code from various vendors in
Eastern Europe. I have unlocked several Motorola phones that way.

Mainly, it means Nokia or Motorola won't divulge unlock codes to you or me.
Or anyway, that's the impression I've always been under :-) .

Cheers, -- tlvp
--
Avant de repondre, jeter la poubelle, SVP.