ATT System 25 Reference Manual

GLOSSARY
Data Endpoint
Two general groups: those having a DTE-type interface, which encompasses almost all of
the data terminal devices; and the group of DCE interface devices which are primarily
modems. However, it must be noted that within each category, control interfaces may also
vary. Refer to Analog Data Endpoint and Digital Data Endpoints for additional information.
Data Module
A data interface device (i.e.,Asynchronous Data Unit) providing a standard interface
between customer-provided data...

GLOSSARY
Equalization
The DS1 signal is shaped so that when it reaches the cable-end it conforms to the
DSX-1 interface power specification.
Erlang
A traffic measuring unit that expresses the load of one or more traffic-handling
devices [36 CCS equals 1 erlang - see CCS (Hundred Call Seconds)].
Extension Number
One- through four-digit number assigned to each voice terminal and data end point in
the system.Also see “Personal Dial Code”
Extended Station
A single-line voice terminal located more than 2000...

GLOSSARY
Foreign Exchange (FX)
A central office other than the one providing local access to the public telephone
network.
Foreign Exchange Trunk
A telecommunications channel that directly connects the system to a central office
other than its local central office.
Foreign Numbering Plan Area Code (FNPA)
Frame
An area code other than the local area code; also known as the “other area code.”
The foreign area code must be dialed to call outside the local geographical area.
Slip
A slip is the deletion or...

GLOSSARY
Immediate-Start Tie Trunk
After establishing a connection with the distant switching system for an outgoing call, the
system waits a nominal 65 milliseconds before sending the digits of the called number. This
allows time for the distant system to prepare to receive the digits. Similarly, on an incoming
call, the system has less than 65 milliseconds to prepare to receive the digits.
Inside Call
A connection between two parties within the system.
Intercept Tone
An alternating high and low tone;...

GLOSSARY
Loop Start Trunk
After establishing a connection with the distant switching system for an outgoing call,
System 25 waits for a short period of time before sending the digits of the called number.
On incoming calls, the received request for service is sufficient to cause the call to route to
a predetermined destination, normally the system attendant group. No digits are received.
MET: (Multibutton Electronic Telephone)
Misframe
Frame in which framing bits where observed to be in error.
Modem
A...

GLOSSARY
Off-Premises Station (OPS)
Ones
An arrangement provided by the local telephone company which permits remote
Terminal Equipment to operate as though it was directly connected to the System 25.
This tariffed service can only be provided for FCC registered single-line voice
terminals.
Density
In synchronous communications systems where clocking is embedded in the data
stream, a required number of signal transitions must occur in order to accurately
recreate the clock at the far end. In the T1...

GLOSSARY
Personal Dial Code
Each system user is assigned a PDC and is allowed to “sign in” the PDC at any voice
terminal in the system as he or she moves about the premises. The PDC may be a 1-,
2-, 3-, or 4-digit number. There are two types of PDCs:
l PDCs assigned to voice terminals -Associated with each voice terminal in the
system.
l Floating PDCs (FPDCs) -Assigned to visitors and those users who do not
have exclusive use of a voice terminal.An FPDC may be signed in by its
owner at any system voice...

GLOSSARY
Public Network
The network that can be openly accessed by all customers for local or long-distance
calling.
Queue
An ordered sequence of calls waiting to be processed.
Queuing
The process of holding calls in order of their arrival to await connection to an
attendant, to an answering group, to a station, or to a trunk. Calls are automatically
connected in first-in, first-out sequence.
RIMS: (Remote Initialization and Maintenance Service)
Random Access Memory (RAM)
A storage arrangement whereby...

GLOSSARY
SAT: (System Administration Terminal)
SIP: (Station Interconnect Panel)
SLAC: (Switched Loop Attendant Console)
SMDR: (Station Message Detail Recording)
Selector Console: (Direct Extension Selector Console)
Signaling
Signaling is the process of communicating channel state information for end-point to
end-point.
Single-Line Voice Terminal
Voice terminal served by a single-line tip and ring circuit (2500 series and 7101A
voice terminals or industry standard Dual Tone Multifrequency equivalent)....

GLOSSARY
Switch
The software-controlled communications processor complex that interprets dialing
pulses/tones/key board characters and makes the proper interconnections both within
the system and external to the system.The switch itself consists of a digital
computer, software, storage device (memory), and associated circuit packs and
special hardware necessary to perform the actual connections.
Switchhook
The button(s) on a voice terminal located under the handset.
Synchronization
Coordinated timing...