@Galaxy4mylife You can swap any tmobile or sprint sim card even metro might work even not active sim card on your unlocked S10 series.. Even if you have unlocked S10 I think you need to have Tmobile and sprint sim card in it.
I hate AT&T. They can't do ANYTHING right. "MoRe fOr YoUr ThInG, tHaTs oUr ThiNg" Nah fam your "thing" is being the worst company I've ever had to deal with in my life. I hope they go bankrupt.