Siemens HIPATH 8000 - Manual (Page 26)

Getting to know your OpenStage phone
26
Trunk keys (on multi-line phones only)
The programmable sensor keys on multi-line phones function as trunk
keys. Each key programmed with the "Line" function is handled as a line.
This means up to 9 line keys can be configured on OpenStage 80 SIP and
up to 8 on OpenStage 60 SIP.
A distinction is drawn here between primary, secondary and phantom
lines. Each of these line types can be used on a private or shared basis
page 27.
Primary line
All multi-line telephones have a primary line. This line can be reached in the
usual manner via your public phone number. Incoming calls are signaled on
this line.
Secondary line
The secondary line on your phone is used as a primary line by another sub-
scriber of the line trunk group. Your primary line, which is configured on an-
other telephone in the line trunk group, simultaneously functions as the
secondary line on that telephone.
Phantom line
Phantom lines are not used as primary lines by any telephones in the line
trunk group. Phantom lines are established when the number of lines pro-
vided by a communications system exceeds the number of available tele-
phones.
To avoid conflict between individual multi-line phones, the functions
"Do not disturb" and "Call forwarding" can only be used for the prima-
ry line.