TAE was introduced in the late 1980s in preparation for the deregulation of the device and telecommunications market in Germany through the postal reform. It was intended to create a defined network termination and allow subscribers to connect certified and suitable devices such as phones, answering machines, modems and faxes to the telephone network themselves. Before this, telephone connections were typically hard-wired, which did not allow for switching devices. Additional devices could only be connected to the telephone network with a special socket (ADo). For testing purposes, the subscriber's initial TAE socket has a passive test connection (PPA). It therefore must not be replaced with a regular TAE socket.
TAE sockets and plugs can be coded differently. They're either F- or N-type. An F-type is intended for telephony. Here the F stands for "Fernsprechen" (telephone). N stands for peripheral devices or "non-telephone" and is intended for any device but phones. NTBAs or DSL splitters, however, are typically connected to the F-socket. U-type sockets are very rare. U stands for Universal and allows both F- as well as N-type plugs to be connected. TAE sockets commonly have several (often three) different socket types such as NFN sockets.