Instructions
Find the coin slot on the payphone. Western Electric models vary in having 1 to 3 slots (for nickels, dimes and quarters) depending on the era it was built.
Check the actual carriage and earpiece on the device. Most older models will have only an ear piece that extends from a cord unless they've been updated and refurbished.
Look for the Western Electric "bell" logo and an AT&T logo. Western Electric was the sole manufacturer for the Bell system and AT&T during the early years of the phone.
Check the manufacture date on the carriage or body of the telephone. Western Electric manufactured telephones the first telephones in the late 1800s until well into the 1990s when the company was dismantled and renamed by AT&T. A payphone manufactured by Western Electric could have been produced at any time during this period.