There are two types of locks.
(1) SIM Lock
This is the lock that allows your phone to only use a SIM card from a specific company. In our case, AT&T or Cingular, but not both. It is the result of anti-competitive pratices and is hard-coded into the core software that comes with your phone.
Fortunately, SPV-Developers figured out how to get rid of it so you can change carries and still have your phone work!
(2) Application Lock
This is a lock that prohibits you from installing certain types of applications. An early Typhoon model, the UK's 'c500' from Orange refuses to install any applications that do not have proper certification. You'll hear the Brits complain every now and then about this problem, but the truth is they got the Typhoon significantly earlier than those of us in the states. Also, their providor, 'Orange' released a tool to application unlock all their phones.
Because the US gets screwed by the stupidity of our oligopoly providors, the "Audiovox SMT5600" - a version of the HTC 'Typhoon' - had slightly newer software. One of the modifications is that most applications *can* be installed with uncertified (ie, free) ones giving you a warning prompt.
For one reason or another, this isn't the same as having a truly application unlocked phone. Some residual lock remains, which prevents the SPV SIM unlocking tool from working. So, to do that, you must first application unlock your phone. Quite a few people have created solid packages including unlocking software, so that should be easy.
I've hypothesized that this half-unlocking we have also plays a roll in our inability to delete "system" files. I haven't had a chance to explore it myself, and the US Audiovox SMT 5600 community is relatively small compared to the UK c500 community, who prefer to agonize over how they get new phones two months after France and contemplate the upcoming c600.
And, yes, I'm quite bitter that the Typhoon is still considered one of the US' best phones at $250 despite its' upgrade being FREE in the UK.
how to unlock application?