Can’t send imessage

[Lisa61]

I am new to Public Mobile. When I try to send a message to someone I always used to use imesssge with it goes through my email?  How do I fix this?

[slusagm]

Remove your old sim card with your old provider, or disable the eSIM

You can then remove the phone number from Settings menu and reboot the phone.  Re-enter the phone number back so iMessage will re-register to fix the issue