I had a similar issue with my AT&T S6 edge + and a friend gave me her verizon note 5. If you log into myatt.com it has clear and easy instructions to enable the use of the Verizon phone. I took the SIM from my S6 and put it into the note 5 before I ever contacted AT&T and had calling and text when they said it would not work until they set it up for me. Make sure your SIM is activated and it will work, however the Verizon Note will give a message about not having their SIM installed. If the new note you received is not locked then that is the best route, AT&T can switch it over for you once you provide the IMEI and SIM from the Verizon phone.