[jdblair]

Its unlikely that it was special-built for the Space Shuttle. Obviously this is speculation, but it most likely was already special-designed for a military application and just re-used in the shuttle. All of those strategic nuclear bombers that used to fly on standby 24/7 needed communications, too.

[kens]

You don't need to speculate. As I explained in the thread, the Shuttle teleprinter was based on the military AN/UGC-74 teleprinter but had many modifications including new three circuit boards for the FSK decoding.

[jdblair]

Ah yes, its right there in the 2nd post! Thanks for the correction.