Can only call six countries w/Simply "Worldwide" ??

I am curious about Cox phone service, particularly international long distance rates.  I already have Cox internet service.

https://www.cox.com/residential/phone/long-distance.html

When I set zip code to 44116 (my zip code) in top right of page - Mexico, Canada, U.K, Philippines, Germany, Italy - that's it.  I noticed if I change Zip to another market like 85705 (Tuscon, AZ) that there is a searchable list of hundreds of countries.

How come my market is limited to six countries?  I contacted Cox Sales department and the representative couldn't explain the restrictions for my zip code.