Teletype for iMessage is perhaps the most "vintage" way to communicate using a smartphone. The app, which is actually an iMessage extension, allows you to send virtual telegrams with a handful of templates to chose from. These include a template recreating telegrams from the U.K.'s Royal Mail and even one from the old Soviet Union. Teletype for iMessage's greatest appeal is its flexibility. Since it is an extension and not a standalone app you don't need to worry if the recipient of your virtual telegram has Teletype installed or not.
Today's world has embraced old fashioned tech when it comes to audio and photography. Messaging is currently uncharted territory, with most new apps choosing to offer new features as opposed to stripping them away. It remains to be seen whether Teletype for iMessage will catch on with emoji-crazed millennials, but history buffs should get a major kick out of it.