All of a sudden I am having issues with UHC Medicare Solutions paying for G0121 or G0105 with appropriate coding. When I call them, they just state that it was coded incorrectly, but won't give any further guidance. I now have several of these that I don't know what to do? Coding for screening colonoscopy G0121 CPT code and V76.51 ICD-9 code is getting denied and G0105 CPT code with V12.72 ICD-9. We bill colonoscopys to Medicare this way all the time and they are paid with no problems. They are telling me that we are out-of-network with them. Do I need to code/bill different for OON?