5.8.4.2. End-of-Dial According to the 1A Procedure 
The 1A dialing procedure is a method of suppressing the DTMF signals
sent by a DTMF user to a remote exchange that can evaluate any DTMF signals.
This is because otherwise incorrect dialing could result. The SIU sends
DTMF signals to the remote exchange.
IMPORTANT:
The 1A procedure is always used when the internal
station is a DTMF device. If the trunk is seized over a CorNet link (circuit
and station on different systems), digital telephones also display this
property (default value).
You can switch the end-of-dial procedure 1A with the COP parameter
NO1A:
- When the parameter is set, the digits are sent to the CO with no delay (also applies to DIP dialing to CO) and the speech path is not switched until after the 1A time expires; the connection switches to the talking state.
- If the parameter is not set, the last digit is sent to the CO but delayed by the 1A time (also applies to DIP dialing to the CO) and then the connection switches to the talking state.