International Calling Charge in Error

I think you may be confusing international long distance calling with calling while roaming. If you are in the USA and call the Dominican Republic, that's long distance. There is a world connect add-on for service that reduces or eliminates the cost of calling from the USA to other countries.

If you are in the Dominican Republic and calling a number, that is calling while roaming and you would be subject to either pay-per-use charges or $10 per day international day pass charges 

Read your usage report

That’s incorrect. I have the Unlimited Elite plan. It states:

Have an AT&T Unlimited Premium® PL, AT&T Premium®, or AT&T Unlimited EliteSM plan? You get unlimited talk, text, and data at no extra cost when traveling in or between these 20 Latin American countries:1

• In Central America: Belize, Costa Rica, Dominican Republic, El Salvador, Guatemala, Honduras, Nicaragua, and Panamá
• In South America: Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Guyana, Paraguay, Perú, Suriname, Uruguay, and Venezuela

While in one of these countries, you can also call and text the U.S. and the 200+ countries included in International Day Pass at no additional cost. Calling other countries will incur long distance call and text charges or pay-per-use rates.

The DR is one of the 200+ countries so calls made from the DR to the DR are free.  Do you see it differently?

because I was in the US when I placed the call.

Were you? Have you ever made calls to DR while you were in the US?

You provided incomplete information in your original post. You did not state you were on the Elite or premium plan which does include roaming in 20 Latin American countries. 

It does not include long distance calls from the USA to the Dominican Republic. 

If you use Wi-Fi calling while in the Dominican Republic, calls using Wi-Fi calling are as if you are in the USA. 

Read your usage report. If you made a Wi-Fi call while in the Dominican Republic and were billed as if you were in the United States, that would have been correct. Your usage report would indicate that a phone call was made using Wi-Fi calling and the phone number in the Dominican Republic

As it turns out, my call from the DR to the DR was made while connected to Wi-Fi.  I don't doubt that you are correct that calls using Wi-Fi are billed as if you are in the USA, but I have spent 30 minutes looking and can't find where that is explained.  

As shown in my cut and paste above, it just says "While in one of these countries, you can also call and text the U.S. and the 200+ countries included in International Day Pass at no additional cost".  Wi-Fi calling isn't mentioned.  

If the Wi-Fi calling exception to "no additional cost" is spelled out somewhere, it seems counterintuitive that you can make a 5G call on a roaming partner's network for free, but if you are connected to Wi-Fi, you would incur a cost.  In any case, I only made this post to inform people of a charge that landed on my bill where after spending time on a call, AT&T agreed to remove it.

formerlyknownas, I appreciate your support explaining this to me.

Very welcome. 

There are support articles and information on how Wi-Fi calling works...

https://www.att.com/features/wifi-calling/