Backup Calling not working (Android 12)

[fillwithjoy1]

I'm using Jio 4G (local sim) which itself supports Wi-Fi calling through hotspot. I'm using Telstra (which supports WiFi calling internationally, roaming sim) and when I connect to a local WiFi, WiFi calling works. So I was thinking alright, lets get Jio 4G to be used as backup calling. Except I cannot seem to enable backup calling for Telstra at all with Jio 4G on. I will mention, I have used another phone and put my Jio 4G sim, to which wifi calling then works on Telstra. Just wondering if anyone knows how to fix this

Handset: Nokia X30 5G
Android Version: 12 (practically stock, except Nokia added some small settings here and there)