Learn how to block outgoing international calling and texting from the United States. Even if you block these services, you'll still be able to receive international calls.
Just contact T-Mobile Customer Service if you want to add this to your line. Keep in mind this service won't block calls to Canada or the US Virgin Islands. This service also doesn't block outgoing international calls if you are roaming domestically on another carrier's network. All charges are considered valid in those scenarios.
If you're looking to block international roaming (usage while traveling outside the U.S.), check out Block international roaming instead.