This is rejection message from the payer is pretty short. It is basically saying they do not know you as a provider. Or, they do not have your NPI on file. Unfortunately, they are not being specific as to whether or not they are referring to you as a billing provider (Box 33) or you as a rendering provider (Box 31 and Box 24J).
You will want to call the payer to make sure they have your NPI on file and/or that you are submitting your claims to them with the NPI that they have on file for you, most likely as a billing provider (Box 33).