Sim not working with a new phone in foreign country

Some countries also have restrictions for phones purchased in them. Some users on other websites have had issues getting foreign SIMs to work with phones purchased in South Korea. The foreign SIMs in some cases were not recognized at all in the phone bought in SK but worked fine in the old phone brought from home. You may need to check with the local carrier in SK to see if there's anything they can do or if there are restrictions on their end.

Additionally, the phone itself won't be in Telus's database either. If it was in Canada, it likely wouldn't be much of an issue but overseas it's hard to say.