I need to reactivate my iPhone

If I said the phone back to factory settings and it doesn’t work, then what do I do because I will not have nothing and can do nothing with my cell phone then

The phone my iPhone 13 is not active I tried making a call it says fail so that means the cell phone is not active so I need to get it reactive so I can receive a six digit code and continue on what I was trying to do

[Re-Titled by Moderator]