Trying to find the source of this: someone recently observed (maybe here on HN?) that a number of communications methods we take for granted in our everyday liv

Trying to find the source of this: someone recently observed (maybe here on HN?) that a number of communications methods we take for granted in our everyday lives started as accessibility options. The example that struck me was text messaging, which allegedly began as a way for deaf people to use cell phones. Anyone know the reference?