[Galaxy S 5 Q&A, Help & Troubleshooting] DanielAlegria:
Hello everybody, sorry if this has been asked I tried searching everywhere and have come up with nothing that has been helpful to me. I am new here so if I'm posting in the wrong place I'll be happy to remove this.

I will try to provide you with every detail but my main problem is this: I have obtained an unlock code I received directly from Sprint for a Galaxy S5 I received from a friend. The friend made sure the device and his account met their qualifications, and he received a six digit "MSL Code" that he was told is the unlock code.

I have been told by Sprint, AT&T, countless YouTube videos and forums that the sequence for unlocking this phone is as simple as 1.) Entering a foreign sim into your device. 2.) When you turn the device on you will be prompted to enter the sim unlock code. 3.) Enter the unlock code and your device will be unlocked.

Of course it's turned out to be way less simple than that. My most obvious problem is with step #2. I

am never prompted to enter the sim unlock code and instead only receive the message "Invalid Sim card."

Okay here is a back story if you want more details: I am on a family plan with AT&T right now that I believe is a good deal and would not like to switch carriers, although AT&T hires some of the biggest idiots I've ever encountered to work in their retail stores and tech support. I have been tempted to switch to Sprint because throughout all of this they have been the only ones to give me straightforward information and any help at all so far.

The Galaxy S5 in my possession meets all of Sprint's requirements to be unlocked and the previous owner received the unlock code directly from Sprint. It should be good to go.

I went to AT&T retail store with the locked device and unlock code for assistance and to make sure the process would go smooth and easy. The first time I was told it's impossible to sim unlock a phone and all I can do is sell the phone on eBay. I called tech support after this and they told me my problem was that I was using the AT&T sim card from my old HTC One, that SIM Card would be incompatible with the Samsung, so therefore I am receiving an "Invalid Sim card" error. The second time I went in I requested a sim card for a Samsung Galaxy S5 because AT&T tech support told me the SIM card in my HTC will not work. The dude grabbed an empty SIM card and gave it to me without asking me for my information or anything about my account and when I asked him about this he told me that it's not necessary, "SIM cards don't have any memory or carry any information on them for the phone to read other than what service the phone is supposed to use". I honestly don't know much about cell phone technology but I knew this was bull**** but he was no further help after I told him I think he might be wrong about that. I called AT&T tech support and they told me that guy was an idiot and to go back to them and request another SIM card.

I don't want to go back into that stupid store until I'm absolutely sure what the **** I need to do to get this stupid phone to work with my AT&T account. Please educate me on how this process works and what the correct steps I need to take are. Thanks a million times in advance for whatever help you can give me, and again let me know if this is being asked in the wrong place I'm still new here.