My understanding is that first sale of an object covered by copyright exhausts the author's
rights in that particular object. The purchaser is buying an object and all its contents and
is no longer bound by the original license.
The purchaser DOES NOT have any additional right to distribute the software contained in the
device (make additional copies), but has the right to resell the device and the copy of the
software that is in it. I don't think that would be affected by, for instance, loading
additional software into the device or removing some of the software in the device. However,
if the purchaser loaded other versions of GPL software into the device, then the distribution
of that software would have to be under the terms of its license.
The point is that the specific copy of the software that the purchaser got from the original
seller is the purchaser's property and can be resold with no obligations under the original
license (in the US).
My understanding from one of the other postings is that Verizon is also distributing updated
firmware and that they may also put a different version of the firmware into the device before
reselling the device. In that case, they would be the original distributor for that copy and
would be bound by whatever license applied.
Note that all of this is speculative - nobody in this discussion seems to know exactly what's
in the device or where they got it, so it's not clear what rules would apply...