[collint]

I'm not sure if the joke is Morse code on a phone, or using two buttons for Morse code.

[JoshTriplett]

Many high-speed CW (Morse) operators use devices with two inputs rather than one (called "iambic paddles"). See https://en.wikipedia.org/wiki/Telegraph_key for various types of Morse inputs beyond the traditional single key.

[collint]

Pleased to be educated :)