Given what you state, you are still using your home carrier SIM and are attempting to use your services via an International Roaming plan provided by your home carrier. Such can be challenging for some carriers to properly configure...I had two "failed" international trips before my prior carrier could properly configure my international roaming.
The challenge is that the configuration that your home carrier must do must be done while your BB is actually on your home carrier network; changes to the configuration cannot be done while you are actually roaming. To make this even more challenging, testing of the configuration cannot happen until you travel and attempt to use it.
This creates a great challenge -- if they configure it incorrectly before you leave your home network, and the testing fails when you travel, then they (your home carrier) typically can do nothing about it until your device returns to your home carrier network. (Hence those two "failed" trips of mine that I mentioned earlier.)
As far as I understand, your only option is to wait until you return home and then talk to your home carrier again, letting them know what happened, and hope that they can fix it for your next trip.
Occam's Razor nearly always applies when troubleshooting technology issues!
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