we sent telex msgs using a telex machine to a sita address for departure messages or delays etc in BMA and Monarch in the 1970's and 80's...
Still done today! Although mostly automated, they still come popping out the printer.
In most old school command line GDS's you can still send a telex by writing it out. Only the hardcore know the syntax though:
#QU LHRKLXX MANKDXX
Its always struck me as an outdated way of communicating. But when you think about it it makes sense. Its a universal language (particularly LDMs, and MVT signals), pretty much every airline and haldning agent around has the ability to use it for their own means, and its relatively cheap.
Apparently SITA charge by the character to send them (they certainly used to anyway). This led to telex operators cutting down the length of their free format messages - the original pioneers of txt spk!
BRGDS - JERBD