3Com VCX Manual page 79

If all the bridge lines are in use, a call to the primary extension rings on a primary
telephone SA line and does not ring on the secondary phone. If all bridge lines and SA
lines are in use on the primary, a call is forwarded to the Call Forward - Busy destination
configured for the primary phone.
Topics in this section describe how bridged calls are handled when certain VCX
features are invoked by the primary telephone user, the secondary telephone user, or
both users.
Do Not Disturb and Bridged Line Calls
If the primary telephone enables Do Not Disturb and a call rings on a secondary phone,
there is no call indication on the primary phone—the telephone does not ring and the
BSA light does not blink. Once the call is answered or put on hold, the primary phone's
BSA light does indicate call status.
If the primary telephone enables Do Not Disturb, a call goes directly to the primary
phone's call coverage point if:
If the primary telephone enables Do Not Disturb and no secondary telephone
answers the call, the call goes to the primary phone's Call Forward destination when
the Call Forward - Ring No Answer ring timeout value is reached.
If a secondary telephone enables Do Not Disturb and other secondary phones are
available (or the primary telephone is available), the call rings on one of the other
phones.
If a secondary telephone enables Do Not Disturb and no other secondary phones
are available, the call rings on the primary and there is no indication of the call on the
secondary phone.
If neither the primary telephone or the secondary phones have Do Not Disturb enabled,
a call rings on both phones.
If the primary telephone user presses the DND button while the call is ringing, it
stops ringing and the BSA light stops blinking but continues to ring on the secondary.
If the secondary does not answer, the call goes to the primary phone's Call Forward
destination when the Call Forward - Ring No Answer ring timeout value is reached.
If the secondary telephone user presses the DND button while the call is ringing, it
stops ringing and the SA light stops blinking but continues to ring on the primary. If the
primary telephone does not answer, the call goes to the primary phone's Call Forward
destination when the Call Forward - Ring No Answer ring timeout value is reached.
If the primary and secondary telephone users both press the DND buttons while the
call is ringing, it stops ringing and the SA light stops blinking on both phones. The call
goes to the primary phone's Call Forward - Busy destination.
If the primary telephone enables Do Not Disturb, a call rings on a secondary phone. If
the primary telephone user disables Do Not Disturb while the call is ringing, the call
All secondary phones have enabled Do Not Disturb
No secondary telephone is available
If the primary does not answer, the call goes to the primary phone's Call Forward
destination when the Call Forward - Ring No Answer ring timeout value is
reached.
If the primary does answer or put on hold, the secondary phone's SA light does
indicate call status.