"This Phone Has NOT Been Unlocked" ???

I am looking at used phones and theres a Sidekick 2 and it says This phone has not been unlocked





WHAT DOES IT MEAN?!?!





Heres what It All Says:


Up for sale here is my used T-Mobile Sidekick II. If you're looking at this auction, you already know what you're looking for. It is in great condition and works great. I used this phone for 1 year and never had any problems with it. I had a protective skin and screen cover


on it the entire time, so it has very little wear. The only wear is some light scratching on and around the lower left button, as can be seen in the picture. With the Sidekick, I am including the original charger, and an additional car charger, and combo car/wall charger, so a total of 3 chargers. Also I am including some extra bumpers for the phone in black, blue, and red. An unused leather carry case and unused earphone are included. All manuals and the original box are also included. SIM CARD IS NOT INCLUDED. THIS PHONE HAS NOT BEEN UNLOCKED

"This Phone Has NOT Been Unlocked" ???
a locked phone means the phone company you got it from you can only use plans and services with that company and no other I.E. if it a t-mobile phone and it's locked you can only use t-mobile services and no other. An unlocked phone is like th L6 sliver i have i use t-mobile as my coverage but if i was to change and go to cingular for example i can still use that phone with the different sim card and everything. catch is just because the phone is unlocked doesn't mean that you can use all the features on it

snake plant