There are obsolete electronics that would be a lot harder to sell, for example CRT TVs - but phones are basically free money.
A complication is that they have so much stock, you'd need to get (road-worthy) transportation to wherever you arranged storage accessible to you.
Maybe the collection could be parted out to multiple buyers, to make some of the higher-value lots sell more easily? For example, separate buyers for the lots of wood, candlestick, and novelty phones, then another buyer pays for right to pick over the remainder for 2 weeks, then maybe it's still worthwhile for an area scrap yard to haul away all remaining stock/trailers/fixtures for free?
Some people will see a market niche in it (existing or not), and bet some $ on that to start a little side business.
Bigger lots + whatever pricing makes it move.
Meanwhile, antique phones, typewriters, cameras, and so on are popular enough that people make replicas: https://www.ebay.com/itm/266280860021