To check the current record simply launch the addon in the contact, company or group detail view and the add-on will show you the different phone numbers of the record.
You can either double-click a phone number if you want to check only this phone number or click the OK button to check all of them.
If the add-on says it is a Do Not Call number, then you can click the Details button to found out in which list the phone number appears if that's any use to you.
The phone numbers that are listed come from your Default ACT! fields to match against list under Options>Preferences