I did not receive a verifying code on my iPhone

For what service? The two factor authentication you have set up on your phone is only for when signing into your Apple Account. Other services such as banks, Google, Government Sites, etc, use their own two factor authentication, so make sure the information you have with them is correct. Some times they will give you the option to receive the code by email and then you will want to make sure it has not gone into a junk folder.

What are you trying to do?