Is this the app in question: https://play.google.com/store/apps/details?id=com.teltechcorp.trapcall? Looks like the usual kind of reviews, most positive but a significant number say it doesn't work. You should definitely visit the developer's Website from the Google Play page and take note of both the subscription prices (ranging from $4 to $20 per month, depending on the plan you choose) and the carriers that it claims to work with.
Yes Dave-in-Decatur that is the correct link. Thanks for the info I will take a look but I definitely don't want to spend money on a subscription for a app that does not work.