No service since 3 weeks

Hello,

I’m french and in Chile since 2 months.

I have an iphone 8 and it worked well for the first month. Then since 3 weeks I don’t have service it’s written « no service » and when I reboot my phone it’s searching for a few seconds and then back to no service.

i verified my options in the settings, and I tried to change my sim card to another phone and it worked well on the other.

I really need some help, thank you.