Title text: Hey, man, the 1670s called. They were like 'Wherefore this demonic inſtrument? By what ſorcery does it produce ſuch ſounds?"
This is a take on the common insult "<year> called and they want their <whatever> back," referring to something out of fashion (used before in comic #875). In this case, the '70s actually called (for an unknown reason), but did not leave a message. Instead, the caller is puzzled because answering machines and especially voicemail were rare or nonexistent in the 1970s, and his telephone has a rotary dial, rather than a touch tone, so he can't "press 1".
Originally telephones had rotary dials instead of buttons. When you lifted the receiver you would hear a tone that let you know you had a connection and you could dial the number, this is the "dial tone." This is the origin of the phrases "dial tone" and "dialing a telephone number". Touch tone phones were introduced in the 1960s, but weren't standard in many places until the 1980s.
The title text plays off the fact that the telephone had not yet been invented in the 17th century. Randall uses the character "ſ", the long S, which takes the place of the modern "s" in the beginning and middle of words; it was used in written English back then.
- Cueball: Nice jacket. Hey—
- Cueball: The Seventies called.
- Out-of-panel: Oh? What'd they want?
- [Cueball looking at phone]
- Cueball: I don't know. They didn't leave a message.
- Out-of-panel: Weird.
- [Person in bell bottoms using a rotary phone to call the present day, with an incredulous look on his face.]
- Voicemail service: If you'd like to leave a message, press "1".