What stage of lock is my Jamin?

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I have a Imate K-Jam that I bought here in the middle east where I am visiting. I bought it out right without a contract etc. It worked fine with my Fastlink sim. I put my USA Cingular sim in and it would not work. I later unlocked my Kjam to install the Qtek rom because it had the bluetooth dialing in standbye fix. After that, my Cingular sim works here (albiet I am sure the charges would be very high if I actually use it to make calls etc). I then bought a Imate Jamin. My Cingular sim works the same as in my Kjam after unlocking it. So I guess I am a bit confused. What kind of lock did my Kjam have that my Jamin doesn't? Does that fact that my Cingular sim works in my Jamin mean that it is completely unlocked? Is the only lock on it the one that would prevent it from having another brand rom installed?

Basically an explaination of the possible locks a phone could have and how to find out what is locked would be great.

Thanks

There are:
- Device lock, preventing from installing other OS.
and
- SIM lock, preventing from using SIM from another operator.
There are also tools to unlock device, SIM and both.
Thats all I know.