Overclocked TI Silent 703 at 1200 bauds?

[CuriousMarc]

I recently acquired a TI Silent 703 on ePay and just fired up. It worked
right away. But I expected it to work at 300 bauds as advertised, and to my
surprise, it clocked at a the head turning speed of 1200 bauds! Did they
hot-rod it later in its product life? It says MODEL 703 at the back, part
no. 2310503-0010. I did not open it up yet.  Is this a hardware mod? Is
there an internal switch that can toggle it between 300 and 1200? 

Marc