Nortel 1000 Features And Services Fundamentals page 380

380 Centrex Switchhook Flash
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Whenever Centrex Switchhook Flash (THF) is invoked, the system checks
for the following:
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If any of the above checks fails, the user hears an overflow tone. After the
tone times out, the original connection resumes.
Operating parameters
This feature is not supported on Basic Rate Interface (BRI) telephones.
THF is not supported on Primary Rate Interface (PRI) or BRI Central Office
trunks.
On Meridian 1 proprietary telephones, once the THF key has been pressed,
all other function keys are blocked. While waiting for the Centrex connection,
only the RLS key or on-hook connection is operative. Pressing the RLS
key or hanging up terminates the original connection as well as the THF
message.
For the analog (500/2500 type) telephones, another switchhook flash is not
allowed once THF has been invoked. A second switchhook flash is treated
as an on hook disconnection.
Only voice calls are supported on THF.
In Italy the DTI2 register recall signal is currently only supported for Type
Approval and is not commercially available.
The 1.5 or 2 Mbit Digital Trunks Interface pack is required.
Because the software cannot recognize which type of Intelligent Peripheral
Equipment (IPE) CO line card (for example, XCOT, or XFCOT) is in use, CO
trunks belonging to different card types should not coexist on the same
Route Data Block (RDB).
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Copyright © 1994–2008, Nortel Networks
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Wide Area Telephone Service (WATS)
CO trunks located at a remote node connected via ISDN Meridian
Customer Defined Network (MCDN) TIE trunks, and
Analog, Digital Trunk Interface (DTI), and DT12 CO trunks.
With analog (500/2500 type) telephones, that the Class of Service
supports THF. With Meridian 1 proprietary telephones, the feature
cannot be activated if a corresponding key is not equipped.
That the telephone is on an active two-way trunk call.
That THF is enabled in the trunk's Class of Service.
The minimum value of the range for the Flash-length (FLH) timer for a
Centrex Switchhook Flash, defined in LD 16 in response to the TIMR
prompt, is 60-1536 milliseconds.
Attendant consoles can activate the feature.
Nortel Communication Server 1000
Features and Services Fundamentals — Book 2 of 6 (C)
NN43001-106 02.04 Standard
Release 5.5 9 May 2008