Daniel Carlson wrote:
I have an antique wall phone which has been modified to work with
today's modular jacks. Problem is, the phone lacks the mounting
hardware on the back which slides over the two slightly protruding screw
heads which are found on a standard telephone switchplate, or wall
plate. Does anyone know of an online hardware store that carries such a
two hole "keyhole" type mount for wall mounting a telephone? I've found
single keyhole mounts, but would prefer the type that's specifically
made for telephones if they're available.

I doubt if you'll find such a thing.

You could buy the cheapest phone you can find and saw it up and make a
rear plate, though all modern phones will be plastic. If you want a
steel plate you'll need to find an old Western Electric wall phone.

Contact "http://www.phonesnthings.com/" and explain what you're looking for.

You certainly could just buy a blank steel switch plate and fabricate
something with the key holes in a few minutes, and mount it to the phone
with some spacers.