Currently, you can only sign up for a postpaid plan after the Alien Registration Card(ARC) is issued. (The same applies to postpaid plans of all mobile carriers.)
LG U+ is preparing to introduce a prepaid plan that can be registered with a passport until the Alien Registration Card(ARC) is issued.
With this new plan, you may switch to a postpaid plan and verify your identity via the PASS app while using the same mobile phone number you’ve used before.