The older phones were certainly built to last. I have the ITT version of a 2500-set sitting next to me on my desk. It's a later modular version from the early 1980s, but still feels hefty compared to today's junk. The old 1962 Western Electric 500 is still much heavier than that though, and the couple of 1970-ish 500s I have aren't that much lighter.

Here's a GPO 746-type phone. Note the different internal layout compared to the 500 sets:

[Linked Image]

[Linked Image]