Contact Center Telecommunications (service sold by AMCS, LLC) - Find Usage and Details

In addition to the charge for the Amazon Connect service, there are also associated telecom charges for public switched telephone network (PSTN) usage. These charges are referred to as “Contact Center Telecommunications” charges on your AWS invoice. These include Inbound & Outbound telephony charges, as well as the DID/TFN daily cost. You can use Cost Explorer to look at the actual usage.

You also get charged for "owning"/"claiming" numbers even if you don't use them. I'm guessing you own three numbers based on the estimate of 87 forecasted usage. It's possible that someone randomly called one of your numbers, thus resulting in the three minutes of charge. You'll want to log into Connect, go to the bottom icon on the left ("Channels"), and select "phone numbers". On the phone numbers page--if you do in fact own any numbers--click the checkbox next to the number and click "Release" in the top-right corner.

Edit: see the "31.0 count for free" in your screenshot. This refers to the number of days of usage in a month (you're "using" the number just by claiming/owning it -- whether or not you take any calls on it). 87 is close to 90, which is why I estimate that you have 3 numbers claimed.