Automatic multiple switch
An automatic multiple switch ( AMS ), also known as a T2 switch, is a junction box with which several telephones can be connected to a single analog telephone connection line.
It is a further development of the AWADo (automatic changeover switch junction box ) that emerged in the 1980s / 90s . It is no longer necessary to connect the W wire ("alarm clock wire"), which is missing on modern telephones anyway. Correct polarity of the a / b interface is also unnecessary .
Automatic multiple switches allow two (AMS 1/2) to four (AMS 1/4) analog telephones to be connected to one exchange line .
When there is an incoming call, all connected telephones ring. The participant who lifts the receiver first receives the call. The other telephones are then switched off and it is not possible to listen in on the call on another telephone. The call can be passed on to one of the other intercom stations by first picking up the handset of the subscriber from a terminal that is not making the call and then hanging up the handset by the subscriber of the terminal making the call. Outgoing calls can be made from any of the connected terminals. If there is no "dial tone" when you pick up the handset, the connection line is already being used by another terminal. The AMS are approved by the Central Office for Approvals in Telecommunications.