You should add international voice roaming and you'll likely need to restart your phone or pop out your Sim card and back in again and restart a few more times if it won't work. Also did you confirm that you had the proper + "country code" when you were texting and connected to a local network?
It really is just the add-on I mentioned via self-serve add-ons to enable it.
But did you have the plus in front of the 1 + number? We're you showing up as connected roaming on your phone? Is roaming enabled in your phone settings?