yeah thats the thing, thats why we need a modded msm tool for someone to create because it just works. there used to be a bounty on it but it got removed from the threads because of rule violation i guessVery interesting. As I thought OnePlus 8T TMO might be the same as OnePlus 8 on this dual sim issue, I looked it up in their threads. OP 8T do have a modified MsmDownloadTool to convert their device to a global version and dual sim works after the conversion, but two slots also share the same IMEI !
*** Use this at your very own risk. *** You will lose all data *** Backup your working modem and persist, just in case *** Read the entire post and follow the steps closely before asking for help. Post all error messages and steps you took...forum.xda-developers.com
The dual sim problem OnePlus 8 TMO faces may not be caused by duplicate IMEI, but other software constrains. Let's dig it further!