Xm radio. I just bought a 2007 Hyundai Sonata with factory installed XM. When I hit the XM button

Question

I just bought a 2007 Hyundai Sonata with factory installed XM. When I hit the XM button it says "XM Loading". But it doesn't do anything else. I called XM and they don't know what to tell me. I am trying to subscribe to the service but without the radio ID I can't.