Nortel DMS-100 Series Maintenance Manual page 399

If the conference call is set up and the test desk disconnects, the two original
lines remain connected. The original lines remain connected without the use
of a conference card.
The following list is a list of events that lead to a conference call that fails to
be set up. The first list contains conditions that cause the sending of a BSY
tone to the test desk. The second list contains conditions that cause the
sending of a reorder tone to the test desk.
Test desk receives BSY tone 60 ipm
— line has an activated custom calling feature
— line connects to an operator, a private branch exchange (PBX), or
another test trunk
— line does not have a double connection option
— line has plug-up option
— line has suspended service option
— line has requested suspended service option
— line has random make BSY option
— line does not have line insulation test option
— line connects to an attendant console
— line is in ringing or digit collection states
— line receives a station test at this time, like the station ringer or silent
switchman test
— line has three-way calling option and engages in a three-way call at
this time
— the test trunk is data entered as type TSTDK and version normal in
table TRKGRP
— the BARGE field of table TRKGRP is set to N (no) instead of Y
(yes)
DMS-100 Family SMS Maintenance Manual XPM10 and up
Trouble isolation and correction 9-35