M-key

M-key is a special key on Zenitel Intercom stations.

Press-to-talk (PTT) control:

• During Conversation: If an operator is pressing the M-key during a call, the audio will be forced in one direction (forced simplex). Releasing the M-key will force the audio in the opposite direction, towards the operator. If the operator presses the M-key briefly, the conversation will return to duplex (handsfree) mode.
• During Group Call announcement: After having dialed a Group Call number, press the M-key to open the microphone
• In Simplex Conference: Press the M-key to talk into a simplex conference (e.g. in communication with Mobile Radio)

Answer button:

• The M-key is used to accept incoming calls

Menu confirmation:

• M-key is used as a "confirm" / "OK" button for many functions.