Can't close flight plan

[flyingdrill]

Just finished an IFR flight into Susanville (near Reno), and was asked to contact Oakland Center, after I landed, to close my flight plan. However, neither the frequency I was on, nor the alternative one shown on a Susanville chart produced any response from the PE controller. I was, by then, around 9000' below his minimum vectoring altitude for the area. Both PE and PEaware showed my complete flight, but I'm not quite sure how I could comply with the controller's request.

[flyingdrill]

As a further, I noticed a similar question had popped up before, and the answer was to close the plan in the air. That's OK, but the controller asked for me to close it after landing - as is normal. However, the published (or PE current) frequency may not work on the ground in PE, and we have no way of knowing, in advance, whether this will be so. It was suggested that a "common" frequency be adopted by PE for these occurrences, and an obvious candidate would be one of the FSS frequencies, which we don't use on PE.