Hi, I hope someone on here can help.

I Just bought a Xiaomi Redmi 15C. Specs says works with Skinny. Old phone was a OnePlus 6T, which stopped working after the 3G shutdown. Issue I have now is I can't make or receive any calls on the Xiaomi phone with the Skinny sim card. Mobile data and send/receive texts works fine. 

I have tested the skinny sim card on a OnePlus 9 and OnePlus 12 and works fine. If I put a One NZ sim card or a Warehouse sim card in the Xiaomi Redmi 15C, calls works fine. I found a post on reddit that mentions dial *#*#86583#*#*. Tried that and made no difference. 

For some reason I can't make or receive calls on the Skinny sim with the Xiaomi Redmi 15C. Is there some setting I am missing? Or is the phone specs wrong and the phone not compatible with skinny?