I'm pretty sure that I have the stock 2005 AM/FM/CD-Player/SAT-read head unit. There is also a Sirius antennae on the roof near the a-pillar. Do I have everything I need to activate Sirius?

Sirius is asking for a ESN/SID number for activation and they can't tell me how to get it. Can someone tell me how to retrieve the ESN? I don't have an owner's manual. Thanks a bunch!

Drew