The Infraphone, invented by Douglas Reddan circa 1960, used infrared light to allow people to communicate wirelessly at distances of several hundred yards. You had to aim your infraphone at another infraphone, which you did by looking through a sight on top of the unit. Then you could talk into the device, just like using a phone.

It's an interesting idea, but I can't really think of a situation when this would provide an advantage over using a radio walkie talkie. Maybe because the signal can't be intercepted as easily? But then there's the awkwardness of having to aim the device. Articles about it frequently suggested it could be used as a wireless intercom.

Eugene Guard - Nov 14, 1960

Palm Beach Post - June 4, 1961

Popular electronics - Feb 1961 (via RF Cafe)