19 May
2009
19 May
'09
12:43 a.m.
On 18 May 2009 at 18:10, Richard wrote:
I don't know what year you're thinking about,
but I was surprised to
see that SPICE was first presented in 1973.
DTMF has its roots in the 1940's network signalling and predates the
transistor, but the model 1500 desk set with 10-key keypad dates from
1963. There were other earlier trial models:
http://www.paul-f.com/weprotot.html
--Chuck