Where do you get the error message? On visible website or app or you get the massage on your phone? If you get it on your phone that means the phone I'd locked or... Please let us know we should be able to help you
I am getting the same problem on my phone. I have an iPhone XR and it’s saying “the sim that you currently have installed in this phone is from a carrier that is not supported under the activation policy blah blah blah please install another sim from a supported carrier or request that this iPhone be unlocked.” Except my iPhone is unlocked and I’ve even used it on visible before a few months back (I was on the $25 party pay plan for several months with visible but canceled it then just recently signed up again and got a new SIM card which is now on the $30 plan/network.) never had any issues activating it last time.