Alcatel System 12¶
System 12 (short: S12) was a digital telephony switch originally developed by ITT in the US in the late 1970s. It has been adapted to the requirements of the German PTT (Deutsche Bundespost) by the German subsidiary Standard Elektronik Lorenz (SEL). The technology was later sold to CGE which became Alcatel in 1987.
S12 was the other digital telephony exchange used in Germany, in addition to Siemens_EWSD. It was deployed from 1985 onwards with analog subscriber lines, and from 1988 onwards [also] with ISDN subscriber lines.