Straight talk has been using 18 t's Network for quite a while, and I ended up connecting it with straight talk, and it absolutely worked and it worked great.
I'm going to show you how to unlock your AT&T.
Here in the settings carrier AT&T, it's going to remove the SIM card, so as you can see it has the AT&T SIM card, let's go ahead and remove that. I'm going to show you what happens when you try and place a different SIM card from another carrier.
What happens when placing a different SIM card
We're going to get this t-mobile SIM card, place it in here, and we're going to place it on the phone. When a phone is locked to a certain carrier, this is what's going to happen when you place in a different SIM card. It's going to go to an activation required screen, go ahead and connect to Wi-Fi.
Let's try to activate the deep phone with the new SIM card, so this is the message that you're going to get, it's going to say SIM not supported, and that's because the phone is locked to AT&T. I'm going to show you how to unlock it, so you can use it with any other SIM card that you wish to use it with.
Let's go ahead and remove the t-mobile SIM card quickly. What we're going to be using is this special unlock chip, we're going to be using this unlock chip to unlock the phone and use it with any company you want to use. In this case, we're going to be using it with t-mobile.
Place the t-mobile SIM card back
Let's go ahead and place the t-mobile SIM card back in now with the unlock chip, and then we're also going to use a code to the activation required screen. It's going to say sim not supported once again. Here what we're going to do is we're going to hit the home button, hit emergency call, and where we're going to type in star *5005*767*0#, and then hit the dial button.
Here is going to show up, you're going to scroll down to edit ICCID, and then here we're going to type in eight nine zero one four one zero three two seven nine five two nine one five by four-five zero, and then hit Send. It's going to say setup, here hit accept, and then now we're going to have to restart the phone.
Use that code one time the phone will stay unlocked
Power the phone off, and the good thing here is that you only have to use that code one time, and then as long as you leave your SIM card with the unlock chip in there the phone will stay unlocked. Once you're ready to power the phone back on there we go. It's going to say activation required.
Once again we're going to swipe and connect to Wi-Fi once again, but it should already be connected. Go ahead and hit next and there we go, it picked up the signal it says t-mobile. It looks like we have to do this, I'm going to set up touch ID later, don't add a passcode, continue, get started, the iPhone is unlocked. You can use it normally now.
It's reading the t-mobile SIM card, it's picking up service, and now you can disconnect from Wi-Fi if you want, and it's going to still have a signal. Let's go ahead and check the data, you see that even the data works.
Let's go to Google, there you go. The font is unlocked, let's try to make a test phone call, welcome to Comcast. As you can see you're able to make phone calls, and use that out right away as long as the SIM card that you put in is activated.
I hope this video helps you out on unlocking your AT&T.
Other web page resource
Unlock a Phone or Device - AT&T Device Unlock Portal: https://www.att.com/deviceunlock/#/