General question regarding unlocking

[virtuouskate]

I recently bought a Samsung Galaxy S6 from T-Mobile. After a massive amount of misinformation from customer care, I canceled my account before the phone was active for 40 days. In addition, their computer system is telling them I never received my phone even though I had it in hand and read them the IMEI from right there on my screen. Long story short, they ended up giving me the phone for "free" (not counting the down payment I'd already made) because they can't unlock it.

The S6 has that horrible Device Unlock app that T-Mobile is doing now. I know there's still a way to get the phone to prompt for an unlock code. I also know people who've tried unlocking this particular phone with a code cannot get their phones to recognize an AT&T SIM. But I'm using the phone on Straight Talk's T-Mobile compatible GSM band. It already recognizes the SIM. It handles talk and text just fine. The only thing I need to unlock is the access point name, so I can change the APN settings to Straight Talk and get data.

Where/how can I get a reliable unlock code? (I saw a post the other day recommending a site that offers refunds if the code doesn't work. That would be awesome since I don't know if it's even possible to get the phone to do what I want.) Is there any other way to change the APN settings?

 

[virtuouskate]

I edited my post for clarity, but yes, the phone needs to be unlocked.