How do I activate my iPhone in another country

What do you mean by "server"? Are you asking how to change your number to a Liberian carrier? If so, contact a carrier?

Or are you asking how to change the region on your Apple ID?

Change your Apple ID country or region - Apple Support

If you mean something else, please explain.

In your iPhone settings/ general/ region and language set the country from there and do the same in your Apple 🆔