Updating old telephones
The bottom compartment held the wet cell battery needed to power long distance calling, and the top ringer box included a magneto crank on the right.
The company also produced similar models in which the microphone box and battery portion were mounted separately on the wall.
For smartphones, the answer is less a matter of physical age (except insofar as the user wants certain phone capabilities) and more about what kind of software the phone can run and whether that software has the latest known vulnerabilities patched.
American Bell Telephone / Western Electric Oak Wall Phone with Magneto crank.
Many locations around the country did not convert from operator-assisted service to direct-dial until decades later. The first subscriber model to integrate the mouthpiece and receiver into a single handset, the 102 was introduced in 1927, followed by the 202 in 1930 (pictured here). These were first made with zinc alloy housings and Bakelite plastic handsets, but a metal shortage during World War II led to a fully-plastic version.
Some retailers refer to this model as the "Lucy phone" because it was used on the set of the popular TV sitcom I Love Lucy.
If you feel comfortable doing do (and when the phone is disconnected), you may want to open up your telephone to ensure the parts inside have been cleaned and upgraded as your seller may have promised.
Some of the companies below also repair and upgrade phones for a fee (maybe you have an old phone in your family you want to work again? The model shown here dates from 1907 or later, when the receiver terminals were first hidden inside the cabinet.