NEC UNIVERGE SV8100 Features & Specifications Manual page 587

UNIVERGE SV8100 Issue 5.0
Dial the extension.
Dialed extension rings.
To place a trunk call using Hot Key-Pad:
The multiline terminal is idle. No need to press speaker key.
Dial the trunk access code, 9 by default, and the external destination number you wish to call.
Hot Key-Pad 1 - 577