Nortel Meridian 1 Manual page 26

Page 22 of 44 E&M tie trunk circuit card
Supplement to 553-3011-210
In both Earth-On and Earth-Off conditions, a grounded 1µF capacitor is
applied to the E wire.
Idle state
In the Idle state, the M wire receives an "Idle signal" from the Option 11 and
is placed in the Earth-Off condition.
Seize
To place an outgoing call, the Option 11 at the near end sends a seizing signal
through the M-wire to the far end. The far end recognizes the seize signal,
busies the circuit against outgoing calls, and prepares to receive digits. The
continued receipt of the seizing signal by the far end is accepted as a "hold"
signal.
Delay dialling/proceed to send
In some system configurations, the sending of address information can be
delayed until the incoming Private Branch Exchange (PBX) is ready to
receive. When the incoming PBX receives the seize signal, it sends a "delay
dialling" signal to the outgoing PBX. Dialling is delayed until the incoming
PBX applies a "proceed to send" signal to the M wire.
Wink start/proceed to send
Wink start can also be used to delay the sending of address information.
When the incoming PBX receives the seize signal, it returns a "wink start"
signal (Earth-on signal of 140 to 290 ms). Dialling is delayed until the
incoming PBX applies a "proceed to send" signal to the M wire.
Dialling
Digits are sent through the near end M wire in the form of 10 pps of the
Earth-Off condition. Dual Tone Multifrequency (DTMF) digits can also be
used for dialling.
Answer
When the called party answers, the far end sends an "answer" signal through
the M wire.
Provisional 1.3 July 1993