Start here: what this board is for
ENEnglishPhone plans and bank accounts are tangled together in Korea — opening one often requires the other, and both usually require an ARC. This board is for working through that.
What people ask about most:
Which banks are workable without a long wait, and which branches have English-speaking staff.
Getting a number: the difference between a regular contract, a prepaid SIM, and an MVNO (altteul phone), and what each one needs from you.
Sending money home, and what people actually use instead of a bank wire.
Card payments, transit cards, and the apps that need a Korean number to register.
If you are in your first week and have no ARC yet, say so. There is a specific set of answers for that situation and it is different from the usual one.