It's the config file which tells the program how it's supposed to find the name of the caller. (Without it, it is only able to guess the nearest city.)

No such config exists for North America because nobody has made one. I think the point was just that it's not your fault that nobody has made one yet.

If you, or someone else, wants to create such a config and post it here, I'd include it in future versions of the program. However, it may not be an easy task, and perhaps the program will need more features for it to be possible. If so, just let me know.