What does TELEX stand for?

Automatic Teletypewriter Exchange Service - of Western Union

Telegraph Exchange - Telecommunications (IAA)

Telephone Exchange (PIPO)

Teleprinter Exchange - Telecommunications (IAA)

Teleprocessing Executive - Telecommunications (IAA)

Teletype

Teletype Exchange (NITA)

Teletypewriter Exchange (SAUS)

Teletypewriter Exchange Service (SAUS)