Thanks for the tip on the ESN. I was not aware of that detail. I had registered my SDS100 by serial number, but had not entered the full ESN. I did that over the weekend, and support responded to my email this morning, stating that the full ESN is, indeed, required, and that I'm all set now. I don't recall the original instructions specifying that the full ESN had to be entered - the paper slip in the box doesn't say anything about it.