Help!

I recently upgraded my iPhone 11 Pro Max to an iPhone 15. With that I also switched plans from AT&T to Verizon. I set up my phone today and everything transferred over. However, my phone number did not switch over. I can make calls to people but no one can call me. I also can’t send messages. I’ve looked online and it says to turn off iMessage and turn it back on but it says “iMessage Activation An error occurred during activation” I’m not sure what else to do. I am going to Verizon tomorrow however I just wanted to post to see if maybe someone can help me before then. Thank you