The handset is more like early to mid 1980's IF we compare it to my AT&T Touch-a-Matic 1600 (1983-85)with the same headset.
It does look like it should have a touch tone version, with all that space on it.
I forget where I found it...but it was one of the other thrift shops- I think it was Park Avenue Thrift. Funny, I've been picking up little things for a year, and forgot the sources. It's part of the disease of thrifting, right? ;-)