Hello if you are reading this then you obviously are looking to buy an Unlocked Sidekick 3.
First off there are 2 ways to unlock the Sidekick 3. The preffered method is done via custom written software and a hard cable unlock. This is the method I use and I highly recommend it. The second way is to have it unlocked via a special code using your IMEI #. If you get one unlocked by code chances are somewhere down the line when T-Mobile update their system your code is flushed out and the phone will relock itself. I get emails from people almost daily that this has happened to and they are asking me to unlock the phone for them. There are some out there claiming to sell Unlocked Sidekick 3's that are cable unlocked. Contact them and have them explain how they are unlocked most will admit to using the special T-Mobile code, that does not make it cable unlocked.
Now once the T-Mobile Sidekick 3 has been unlocked you are only going to be able to make and recieve calls, and send and recieve text messages. The internet functions will not work. Only if you use T-Mobile can the internet functions work. Dont let someone try to tell you different. Once you recieve the phone you are probably going to get one of 2 messages after you put your simcard in and power it up. The first will say waiting for activation, The next will be GPRS services unavailable. Read whats nest to take care of that: Power the phone off then on again. After it is onand you see the waiting for activation screen press and hold the menu key.(THE BUTTON ON THE LEFT SIDE OF THE PHONE THAT HAS THE 3 BARS ON IT)While holding that button down press and hold the L key on the keypad then let them both go. You may need to do this a couple of times. That should get rid of the waiting for activation screen. Do not worry about the GPRS settings, those are internet related and you cant use the internet with an unlocked Sidekick 3. Just click the check key or the bottom right key to make that screen go away.
Lastly: Beware of those claiming to sell Brand New Sidekick 3's in the box. Read the listing fully, read the feedbacks. Many of these people get their phones from the same place I do. Alot of the large powersellers on ebay sell refurbished phones as Brand New. Check their feedbacks carefully. Hope this guide helps answer some of your questions. And dont be afraid to ask questions when making a purchase. Your spending alot of money on a phone and you deserve to know what you are getting. I promise if you buy from me, I will address any and all questions you ask. I also am willing to give my phone number as its sometimes easier to talk by phone rather than email. Check my feedbacks about what people say about my phones. This is what I do for a living and in my eyes the customer always comes first.
Thank you and God Bless...