which countries are included in the Magenta 55 inluded international plan

It’s easier to list the countries that are not included: You can look them up here https://www.t-mobile.com/coverage/roaming Essentially, any place that 99% of people would want to go is included, except ships, planes and Cuba.

Cuba$

Solomon Islands*

Norfolk/Antarctica/AET*

Diego Garcia*

North Korea*

Tuvalu*

Somalia*

Eritrea*

Central African Republic$

Cruise Ships and Ferries$

Airlines$

Djibouti$

Iran*

$=expensive

*=no disponible