ATT System 25 Reference Manual

							Pooled Facility - Dial Access
Administration Requirements
Voice Terminal Port:
l Restrictions - Refer to “Calling Restrictions” feature description.
Trunk Port:
l Assign facility access codes.
l Allow dial access for facility (yes or no).
November 19952-259 
						

							Features and Services
Pooled Facility - Direct Access
Description
This feature allows multiline voice terminal users to access a common pool of trunks via a Direct
Facility access (FACILITY) button.
Upon pressing a FACILITY button and going off-hook, a multiline voice terminal user is connected
to a common pool of outside trunks (i.e., CO, FX, WATS, tie). If the Status and I-Use LEDs
associated with the button light steadily, the user may complete the call. If no idle trunk is available
(facility busy indication), an attempt by the user to originate a call will be denied and the I-Use
indicator will be Off. A user requiring access to several different trunk pools must have a separate
FACILITY button for each pool.
If all trunks in a pool are busy, the Status LED will be lighted. The user may press FACILITY and
remain on-hook to receive the busy-to-idle reminder when a trunk becomes available. The busy-to-
idle reminder is a short burst of tone that will be heard when a trunk in the pool becomes available.
When Prime Line Preference is assigned to a FACILITY button, the button must be pressed to
invoke the busy-to-idle reminder, even though the I-Use LED is lighted.
Refer to the “Trunk Groups” feature description for additional information.
Considerations
Pooled Facility-Direct Access provides easy access to the exchange network for users who make
many outside calls. The feature eliminates the need to dial a facility access code. In addition, the
associated status LED provides pool busy/idle status and the busy-to-idle reminder.
Interactions
The following features interact with Pooled Facility-Direct Access.
Automatic Route Selection (ARS): Multiline voice terminal users who have presses FACILITY to
activate busy-to-idle reminder must wait until all queued ARS users have been serviced.
Equal Access: Equal Access calls are allowed from toll-restricted stations that have outward
calling capability via pooled facilities (701 and 801 trunks) administered with “ORIGINATING LINE
SCREENING.” Originating Line Screening is a service provided by the Local Exchange Carrier
(LEC), identifying the call as one which should not have the operator bill the originating facility.
Facility Access Restriction (see “Calling Restrictions”): A trunk group may be reserved for a
group of users by dial-access restricting the trunks. In this way, only users who have a FACILITY
button, a Personal Line appearance, or who use ARS can use the trunks.
Line Selection (Prime Line Preference): Pressing a FACILITY button to invoke the busy-to-idle
reminder overrides Prime Line Preference.
Toll Restriction (see “Calling Restrictions”): Toll-restricted voice terminals receive standard toll-
restriction treatment on all FACILITY buttons.
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							Pooled Facility - Direct Access
Administration Requirements
Voice Terminal Port:
l Assign Direct Facility Access (FACILITY) buttons.
l Restrictions—Refer to “Calling Restrictions” feature description.
Trunks:
l Assign Facility Access Codes.
l Allow dial access for facility (yes or no).
November 19952-261 
						

							Features and Services
Power Failure Transfer (PFT)
Description
This feature provides service to and from the CO for a limited number of prearranged single-line
voice terminals during a commercial power failure (or when voltage drops below 90 volts for longer
than 250 milliseconds) and during other service interruptions. Any loop start or ground start trunk
may be arranged to terminate at a specific station on a one-to-one basis. When a failure occurs,
these prearranged connections are made, bypassing the system and connecting terminals directly
to the CO trunks. System features and restrictions are not available during this time.
The system supports up to four Emergency Transfer Units (ETUs). Each ETU can provide up to five
voice terminals with direct connection to CO trunks.
When the system connects to dial pulse trunks, only rotary sets may be used to support Power
Failure Transfer (PFT). When the system interfaces the CO via touch-tone trunks, touch-tone
single-line voice terminals are used as PFT stations.
When power is restored, the following will be restored to their previous state:
1. Night Service mode (on or off).
2. User-programmed Flex DSS numbers.
3. PDCs signed in at a “home station” or an “away station” remain signed in there; if Forwarding
has been activated for a station, it remains in effect.
4. If a voice terminal has been removed/not removed from a DGC group, the terminal will remain
in that state.
5. User-programmed Repertory Dialing numbers.
6. All system/station features programmed through system administration.
Considerations
Power Failure Transfer provides emergency incoming and outgoing telecommunications service to
a number of predesignated single-line voice terminals.This is particularly important for
organizations providing public services such as fire, police, medical, etc.
Hardware Requirements
The 10B Emergency Transfer Unit (ETU) in Figure 2-38 supports up to five Power Failure Transfer
(PFT) sets and a DID make-busy function. Up to four ETUs can be supported for a maximum of 20
PFT sets. The sets can be connected to selected Loop Start or Ground Start trunks. If Ground Start
trunks are used, a KS 23566,L1 Ground Start Button must be provided at each PFT set.
2-262November 1995 
						

							Power Failure Transfer (PFT)
Only FCC registered single-line voice terminals may be used for PFT stations. Rotary sets
must be used for dial pulse PFT trunks; touch-tone sets must be used for touch-tone PFT
trunks.
In the event of a Power Failure Transfer (switch has lost power or a major fault has
occurred) a contact closure is provided to the Central Office (CO) over a dedicated pair of
wires.The CO then makes busy all DID trunks.
When power is restored, the closure is
removed and the CO restores DID service. External alarm contacts are provided on the front
of the ETU for use as required.
Note:It is recommended that customers with DID service make provisions with
their CO to provide this arrangement.
The ETUs are mounted on the cross-connect backboard.
Connections are via 25-pair
receptacle-ended (CO and SIP) and plug-ended (switch line and trunk) connectors. Modular
jacks are provided for the -48V control signal from the CPU (Call Processor Unit) and for
additional ETUs. Screw terminals are provided for the connection of external alarms.
When calculating Unit Loading (see Section 5,“Unit Loads”), all ETU loading counts against
Cabinet 1.
The 106 ETU is mounted on the cross-connect field as shown in Section 6, “Environmental
Requirements.”
ETU Power Failure Transfer connections are shown in Figure 2-39. Part (a) on the figure
shows a single-line voice terminal that has been connected as a Power Failure Transfer
station. In normal operation, the Call Processor CP supplies -48V dc to the ETU. The voice
terminal is connected through the ETU to the station port CP and can support all calling
activities.The trunk connection through the ETU to the trunk port supports normal trunk
calls.
Part (b) on Figure 2-39 shows the ETU connections when a Power Failure Transfer has
occurred. The transfer is initiated by the removal of the -48V dc to the ETU. All connections
through the system are dropped, and direct connections between PFT stations and CO
trunks are established. A contact closure toward the CO makes all DID trunks busy.
When the system is again able to process calls, normal service is automatically restored
A multiple ETU arrangement is shown in Figure 2-40. As discussed earlier, separate -48V dc
control signals from the Call Processor are provided via legs 7 and 8 on Octopus cable C2.
The 25-pair cable from the Analog “Line” CP provides connectivity for eight voice terminals
at the Line input to the ETU. Since the ETU supports only five PFT stations, three of the
voice terminals are wired straight through the ETU and are not switched during service
interruptions.A similar condition exists for the 25-pair cable (D) from the CO Trunk CP to
the Trunk input of the ETU. Three of the eight trunk port appearances are wired straight
through the ETU to the CO and are not switched.Trunk ports connected by legs 2 and 3 of
the splitter cable are wired directly to the TAE Block.
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							FEATURES AND SERVICES
Figure 2-38.10B Emergency Transfer Unit (ETU)
2-264 
						

							Power Failure Transfer (PFT)
SYSTEM 25
CABINET
TRUNK
PORTTAE
CALLPROCESSOR
ETU
ETU TO SWITCHETU TO
25-PAIR(TRUNK)CO
-48V
CPU
TOADDITIONALADDITIONALETUsETU
CENTRAL
OFFICE
25-PAIR
OCTOPUS
ETU TO SWITCH(LINE)
ETU TO
SIP
STATION
PORT25-PAIRCABLE
PART OF SIP
858A
ADAPT.
UP TO FIVE POWER FAILURE
TRANSFER (PFT) STATIONS
(REGISTERED SINGLE-LINE)
(a) ETU CONNECTIONS (DASHED LINES) NORMAL OPERATION - (NO PFT)
(TRUNK SUPPORTS STANDARD CO CALLS)
ETU
TAE
-48V REMOVEDCENTRAL
OFFICE25-PAIR
TO PFTSTATION
(b) ETU CONNECTIONS (DASHED LINES) ON PFT
Figure 2-39.Emergency Transfer Unit Connections
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							FEATURES AND SERVICES
NOTES:
1. TRUNK AND STATION CONNECTIONS TO ETU 2-4 ARE SIMILAR TO ETU (1).
2. THREE OF EIGHT STATION LINES (FROM ANALOG STATION CP) AND THREE OF EIGHT TRUNKS
(FROM CO TRUNK CP) WHEN USED ARE“FED-THROUGH” ETU, THEY ARE NOT SWITCHED IN THE EVENT
OF A POWER FAILURE.
3. MAXIMUM ETU(S) = 4, MAXIMUM PFT STATIONS PER ETU = 5.
Figure 2-40.Multiple ETU Arrangements
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							Program
Program
Description
This feature enables system users to store numbers for access by feature buttons or code
dialing. Multiline voice terminal users can program numbers on REP DIAL and FLEX DSS
buttons.Both multiline and single-line terminal users can store Personal Speed Dialing
numbers. FLEX DSS buttons provide access to inside extension numbers only; REP DIAL
buttons and Personal Speed Dialing are used for account codes and outside numbers
(maximum of 28 digits and 25 digits, respectively).
Special Characters
The following special characters may be used in Repertory Dialing and Personal Speed
Dialing numbers:
CHAR.USED IN REPERTORY DIALING NUMBERS
VProduces a 1.5 second pause.
— Since System 25 does not have a Dial Tone detector.
judicious use of the pause character will help to ensure that
intermediate Dial Tones are obtained before more digits are
sent.
— The pause character should not be programmed for internal
calls.
# VTransmits an actual “ V ”.
# #Transmits an actual “ # ”.
# 1xxRepresents a System Speed Dialing code (where xx = 00-89) or a
Virtual Facility code (where xx
= 90-99). If using a Virtual Facility
code, it may appear only at the beginning of the stored number,
# 2xRepresents a Personal Speed Dialing code (where x = 0-9).
# 3xRepresents additional Personal Speed Dialing codes (where x = 0-9).
# 8Marks the beginning of End-to-End Signaling. (System begins
transmitting touch-tone signals to the far end switch.)
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							FEATURES AND SERVICES
CHAR.USED IN PERSONAL SPEED DIALING NUMBERS
VProduces a 1.5 second pause.
—  Since System 25 does not have a Dial Tone detector,
judicious use of the pause character will help to ensure that
intermediate Dial Tones are obtained before more digits are
sent.
—
The pause character should not be programmed for internal
calls.
# V
Transmits an actual “ V ”.
# #Transmits an actual “ # ”.
# 1xxRepresents a System Speed Dialing code (where xx = 00-89) or a
Virtual Facility code (where xx= 90-99). If using a Virtual Facility
code, it may appear only at the beginning of the stored number.
# 8Marks the beginning of End-to-End Signaling. (System begins
transmitting touch-tone signals to the far end switch.)
Programming Procedures
Program mode may be entered either of the following methods:
l At any voice terminal, by dialing the programming access code (#4).
l At terminals equipped with a Test/Program switch, by moving the switch to position
P; this method cannot be used at Switched Loop Attendant Consoles (SLACs).
If the code is used to enter program mode, the terminal remains in program mode until the
user goes on-hook or a timeout occurs.If the switch is used to enter program mode, the
terminal remains in program mode until the switch is returned to the midpoint between P and
T; the system will send a single-ring reminder every 60 seconds until the switch is
repositioned.
Voice terminals equipped with a display enhance the programming procedure by displaying a
prompt on the screen and then the digits as they are dialed. Refer to “Interactions” for
additional information.
Programming a number always removes the number that was previously stored in the same
location. If a user wants to remove an old number and not replace it with a new one, Step 3
in both of the following procedures should be skipped.
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