Activate SIM card from overseas

Not until in the us 

Actually, you should be able to activate the SIM card. Since you can activate online at att.com/activate, if you can get to that web page, you should be able to activate the SIM card and get a number assigned. However, you won’t be able to purchase a plan and even if you could, It won’t do any good. You won’t get service because prepaid doesn’t roam in South Korea.

@sandblaster

That’s fine, I’m not looking to actually utilize the plan until I re-enter the US; I just need a valid US-based phone number to authenticate purchases and what not from time to time.

The customer service representative I spoke to said that even if I get my SIM card shipped to Korea and I attempt to activate it online via att.com/activate, I wouldn’t be able to complete the process because they would require the default 4-digit PIN sent to me via SMS. So, there’s no international roaming available for Korea, I thought that I wouldn’t be able to activate the SIM card while overseas.

Is this actually the case? I’m getting a lot of conflicting information online.

if anybody would know it would be @sandblaster 

What they mean by complete the process is logging into your account and purchasing a plan. That you won’t be able to do until you are in the US but you can activate the SIM card and get a number. You have 30 days to purchase a plan after activating the SIM card.

The customer service representative said as long as I'm able to purchase a Prepaid plan with a VPN, it's fine, but I wasn't sure if they meant an official AT&T VPN or just any random VPN that allows me to log in and purchase a Prepaid plan since that seems kind of sketchy.

From my memory of activating and paying for prepaid, text messages are sent for assigning a login code.  I can't see how you can start service and pay for a plan, receive a login code, with no text service.  

Account access is blocked from most locations abroad. Using a VPN to a US based network is a possible workaround. It does not matter who provides the VPN. However, if you need to receive a text to log into your account, a VPN won’t matter.

Would having someone else set up the SIM card on their device be a possible workaround, or are there issues with how the SIM card is first registered? I can use a VPN to purchase a plan and sign up for an account, but since the only obstacle is the lack of text service out here, I was thinking someone could activate the new SIM card on their device and send it to me. Barring that, I also considered sending my phone to family in the US, have them complete the process there, and ship my phone back here.

thats possible but seems like a lot of work for something you cant use until your back in the states