ATT System 25 Reference Manual

TECHNICAL SPECIFICATIONS
Indicator Lamp Signals
The following lamp signals are provided at multiline voice terminal and ATL
telephone line appearances:cordless
LAMP SIGNALPATTERN (In Milliseconds)MEANING
DarkOffInactive
LightedOnActive
Flashing500 on, 500 off; repeated
Ringing
Broken50 on, 50 off; repeated,Transfer/Conference
Fluttering(gated on/off every 500 ms)in progress
Wink350 on, 50 off; repeated
Hold
5-11 

TECHNICAL SPECIFICATIONS
Port Specifications
The following tables provide interface specifications for System 25 line and trunk port
circuits:
DATA TERMINAL PORTS (Note)
STATION TYPECIRCUIT PACKDATA TERMINAL SPECIFICATIONS
EIA RS-232 Device ViaData LineRS-232 device must furnish
ADU(TN726)signals on ADU pins 2 (TD)
and 20 (DTR) and ground on
either pin 1 or 7. The ADU
furnishes signals on pins 3
(RD) and 8 (CD). The CD
signal is also tied to pins 5
(CTS) and 6 (DSR). Some
data terminals may require...

TECHNICAL SPECIFICATIONS
Port Specifications (Contd)
DATA TERMINALS
(Do Not Require Local Power)
DATAREQUIRES Z3A1REQUIRES
TERMINALor Z3A2 ADUZ3A4 ADU
AT&T
4410
X
4415X
510AX
ADMs
3A
X
31X
ADDS
Viewpoint *
X
ConCept
HDS 108
X
Datamedia
Elite 1521
X
Hazeltine
1510
X
Hewlett Packard
2621A
X
2623AX
2640X
2645X
2645AX
Teletype
BLIT/1 (68000 based)
X
5620 (MAC-80 based)X
5420X
* Requires Originate/Disconnect Switch.
5-13 

TECHNICAL SPECIFICATIONS
Port Specifications (Contd)
5-14
VOICE TERMINAL PORTS
STATION TYPECIRCUIT PACKSPECIFICATIONS
Tip and RingTip Ring Line
Single-Line(ZTN78)l 1-Pair Interface (Tip and Ring)
Sets
(Analog)
l Analog signals modulated over DC loop
l Loop Voltage: 24 V dc
l Signaling: Dual Tone Multifrequency (DTMF)
or Dial Pulse
l REN (max.): 1.2
l DC Current (max.): 35 mA
l Loop Range (24 AWG): 2,000 feet
l In-building service only
Tip and RingAnalog Line
Single-Line(TN742)
l 1-Pair Interface (Tip and...

TECHNICAL SPECIFICATIONS
Port Specifications (Contd)
VOICE TERMINAL PORTS (Contd)
STATION TYPECIRCUIT PACKSPECIFICATIONS
MET SetsMET Line
(Hybrid)(TN735)l 3-Pair Interface
1-Voice pair
2-Control pairs
l Analog Voice, Digital Control/Signaling
l Power: Phantom Power Over Data Pairs
l Bipolar Signaling With 0 V dc Offset
l 1 MHz Nominal Signaling Rate
l Loop Range: 1000 feet
(In-Building service only)
MERLIN®ATL Line
System Sets(ZTN79)
l 3-Pair Interface
7300H Series)(TN762B)1-Voice pair
Hybrid)1-Control...

TECHNICAL SPECIFICATIONS
Port Specifications (Contd)
VOICE TERMINAL PORTS (Contd)
STATION TYPE
ATL
Cordless
Telephone
CIRCUIT PACK
ATL Line
(ZTN79)
SPECIFICATIONS
Handset to Base 1000 feet clear area
Base station:
l 3-pair Interface
1-Voice pair
1-Control pair
1-Power pair
l Analog Voice, Digital Control/Signaling
l Bipolar non-return to zero line-coding
l 40 kHz Nominal signaling rate
l Loop Range: 2000 feet
l In-Building and In-Range Out-of-Building
(IROB) services only (Local power required
when...

TECHNICAL SPECIFICATIONS
Port Specifications (Contd)
TRUNK PORTS
TRUNK TYPECIRCUIT PACKSPECIFICATIONS
Auxiliary TrunkTN763
l Capacity: 4 Circuits
l 3-pair Interface:
Voice (T, R),
Signaling (S, S1),
Status (SZ, SZ1)
Direct InwardTN753
Dialing (DID)
l Capacity: 8 Circuits
Trunk
l 2-wire (600 Ohm Fixed
Impedance) Transmission
l Signaling: Wink Start, Delay Dial,
or Immediate Dial. Accepts Dial
Pulse Signals only
l Incoming Service only
Tie TrunkTN760B
l Capacity: 4 Circuits
l Supports Type I E&M, Type I...

TECHNICAL SPECIFICATIONS
Port Specifications (Contd)
TRUNK PORTS
TRUNK TYPECIRCUIT PACKSPECIFICATIONS
DS1 InterfaceTN767
l Capacity: 24 Circuits
l 4-Wire Transmission
l 3-pair Interface:
Transmit
Receive
Loopback
Ground StartZTN76
Trunk
l Capacity: 8 Circuits
l 2-wire (600 Ohms or RC Balance)
Transmission
l Network Signaling: Ground Start
l Two-way or Incoming-only Service
Loop StartZTN77
Trunk
l Capacity: 8 Circuits
l 2-wire (600 Ohms or RC Balance)
Transmission
l Network Signaling: Loop Start
l Two-way...

TECHNICAL SPECIFICATIONS
Recommended Central Office Trunk Facilities
The following table provides recommendations for CO trunks based on the number of voice
terminals in the system and the calling traffic.
CALLING TRAFFIC
VOICE
TERMINALS
20
25
30
40
50
60
70
80
100
120
140
160
180
200
LIGHT
TRAFFIC
3/3
3/4
4/4
4/4
5/4
5/4
5/5
6/5
6/5
7/6
7/6
8/7
8/7
9/8
MEDIUM
TRAFFIC
4/4
5/5
6/5
6/6
7/6
8/7
8/7
9/7
10/8
11/9
12/10
13/10
13/11
14/12
HEAVY
TRAFFIC
5/5
6/6
8/7
9/8
10/8
11/9
12/10
12/10
14/12
16/13
17/14...

TECHNICAL SPECIFICATIONS
Analog Transmission Characteristics
Frequency Response:
(Station-To-Station or Station-To-CO Trunk, relative toloss at 1 kHz)
FREQUENCYLOSS
60 Hz>20 dB
200 Hz