Roaming SIM (South Korean) not working on Telus profile - Worked fine on Koodo

Hi everyone,

I’m experiencing a strange network issue after switching my service from Koodo to Telus.

Device: Samsung Galaxy S24 (Canadian model)

Current Setup: Telus (Main) + South Korean SIM (Roaming)

The Issue:

My South Korean SIM card, which I use for international roaming, has completely lost its signal since I switched my carrier to Telus. It shows "No Service" or appears to be blocked from the network.

The Context:

When I was with Koodo, this exact same Korean SIM worked perfectly on this exact same S24 device. I had no issues picking up roaming signals.

As soon as I switched to Telus, the Korean SIM can no longer find or register on any network.

Since Koodo and Telus share the same network infrastructure, I am confused as to why the carrier profile change is affecting my secondary SIM's ability to roam.

What I’ve tried so far:

Rebooted the device multiple times.

Performed a Network Settings Reset.

It feels like the Telus carrier profile on the S24 might be more restrictive or has a different configuration regarding roaming handshakes compared to the Koodo profile.