Unfortunately, I tried those very numbers and ran into the same problem that I've stated above:

"Now I am in a foreign country and when I tried to call that number, using the correct country code, I get the local 'unable to complete call' message in Spanish."

My call records show that I had actually tried that number three times before I tried again because you suggested it.
I tried the number using my original Verizon SIM card and global roaming turned on.
I tried the number using the foreign SIM card I obtained here.
I even tried the number using a landline.

None of them worked.

Today is a major national holiday here and I do not have access to someone else who will let me try it on their cellphone.