NEC XN120 Feature Manual page 196

Features
n Operation
To place a call over a trunk group:
1. At system phone, press a SPK key.
OR
At single line telephone, lift handset.
2. Dial 804.
3. Dial trunk group number (1-9 or 01-25 ).
4. Dial number.
OR
1. Press trunk group key (PGM 15-07 or SC 852: *02 + group)
2. Dial number.
To answer an incoming trunk group call:
1. Lift handset.
2. Press flashing trunk group key.
Features Manual
194