Text Messaging

I just switched from an iPhone 8 to an iPhone 13 mini, and also switched from T-Mobile to Verizon. Everything transferred smoothly, except for sending messages on the Messages app. For both me and my sister who also switched, our texts are sending as our iCloud email address instead of our phone number. I went to Messages in Settings and tried to change Send & Receive from my iCloud email to my phone number, but it said “Activation unsuccessful. Turn on iMessage to try again.” I turned off an on iMessage, but it still didn’t work. I powered off an on and tried again, but it still didn’t work. Earlier, I got a text that the transfer of my phone number was successfully completed, so it shouldn’t be a problem from the carrier. My mom also switched the same way my sister and I did, but hers works. I’m just wondering what I can do to make it work.