Messages going to wrong number on account
I recently added a line and gave that person my old iPhone. I setup the new phone under my number and switched the sim cards per the AT&T sales person. Now when my family and friends try to text me, the messages are going to the other person with my old iPhone. They have the new sim card and I have my old sim card from the iPhone. How can I fix this so messages being sent to me, come to me and not the other person?? Thank you!