You want to use your Samsung Galaxy S8 Plus during your vacation or business trip outside the USA. But you can not because it is SIM Locked to T-Mobile Carrier.
No problem you can use it with any SIM card worldwide if you Unlock it, And this guide will show you how to SIM unlock your Galaxy S8 Plus using the T-Mobile Device Unlock application.
The explained steps in this Guide will help you to Factory Reset Samsung Galaxy S8 Plus. This Samsung Android Smartphone comes with more than one Model Number, So you can apply the same steps on:SM-G965F (Europe, Global model with single SIM card). SM-G965F/DS (Europe, Global model with dual SIM cards). SM-G965U (USA carries like AT&T, Verizon, Sprint, T-Mobile …etc). SM-G965W (Canada). SM-G9650 (China). SM-G965J (Japan). SM-G965D (Japan). SM-G965N (South Korea).