Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via frequency channels
Reexamination Certificate
1998-08-19
2002-11-19
Olms, Douglas (Department: 2661)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via frequency channels
C386S349000
Reexamination Certificate
active
06483855
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to communication content recording apparatus and method of recording communication contents such as speech data, etc. to be transmitted through a communication line.
2. Description of Related Art
Various dealings using telephone lines have been made in financial institutions such as banks, securities, etc., telephone marketing such as telephone-ordering and public undertakings such as horse racing, etc. In such a case, communication contents are usually required to be recorded in order to check them again or leave them as evidence. Therefore, communication content recording apparatuses for recording communication contents without affecting the persons using the telephonic communications have been hitherto utilized.
In this type of communication content recording apparatuses, the start and stop timings of a communication recording operation are controlled by surveying the signal level on a telephone line or surveying the off-hook/on-hook operation in order to record communication contents without affecting the operations of existing communication systems as in the case of DN-08R and DN-09R models produced by Nippon Columbia Co., Ltd., or Japanese Laid-open Patent Application No. Hei-5-234247.
Recent developments in digital technologies have promoted propagation of ISDN (Integrated Services Digital Network) as a communication network in which various different services such as telephonic communication services, data communication services, etc. can be connected by using the same digital exchanger and digital bus. ISDN transmits information while digitizing the information, and thus ISDN can perform higher-speed communications with less signal deterioration than analog lines. Here, ISDN will be briefly described.
ISDN has a signal channel (D channel) for transmitting control information such as call control information, etc. and an information channel (B channel) for transmitting user information. Two types of interface are provided as interfaces of ISDN. One is a basic interface (BRI: Basic Rate Interface) comprising one D channel and two B channels, and the other is a primary rate interface (PRI) comprising plural B channels and a D channel.
In a user
etwork interface (I interface) of ISDN, layer
1
to layer
3
are defined for the connection condition between a communication terminal unit and ISDN. The layer
1
to layer
3
are compliant with a 7-layer model serving as a basic reference model of Open System Interconnection (OSI) defined by ISO (International Standardization Organization), and based on basic layers of a physical layer, a data link layer and a network layer which are associated with control of communication networks, thereby enabling communications among various communication equipment.
The layer
1
is applied to an information channel and a signal channel, and an electrical/physical condition to connect a communication terminal unit to a digital line terminal unit (DSU: Digital Service Unit) is defined in the layer
1
. In the layer
1
are specifically defined a wiring construction, a frame structure, a transmission path code, signal channel access control, frame synchronization, electrical characteristics, power supply conditions, etc.
In the layer
2
, information transmission management for implementing transmission of information to be transmitted/received through a signal channel between a communication terminal unit and ISDN is defined. This is called LAPD (Link Access Procedure on the D-channel). By establishing the link between the communication terminal unit and ISDN in the layer
2
, “call” of the information channel can be established on the layer
3
as described later. Specifically, a frame format, a frame type, an information transmission procedure, a management procedure of a terminal endpoint identifier (TEI), etc. are defined. In the frame format, there are provided an information frame for carrying out information transmission in the layer
3
, a surveying frame for checking transmission/reception of the information frame and making a re-transmission request, and an unnumbered frame.
FIG. 11
is a diagram showing the structure of an LAPD frame in ISDN. As shown in
FIG. 11
, a frame based on the LAPD protocol contains an address portion, a control portion (containing sequence number), an information portion and a frame check sequence portion for detecting an error, which are sandwiched between flags (0111110).
In the layer
3
, information on an information channel, which is transmitted between communication terminal units after the link is established in the layer
2
, is defined. Specifically, the content of the information format, the control of a line switching connection, a packet communication procedure, etc. are defined. The line connection and the link between ISDN (network) and each of communication terminal units are established by the layers
1
and
2
, and “call” between communication terminal units through ISDN is established by the layer
3
.
In the layer
3
, messages indicating call control, etc. are transmitted on the basis of the information frame. As messages indicating the call control, there are provided a call-setup message, a call proceeding (call-setup reception) message, an alerting message, a connect message and a connect acknowledge message, which are to establish a call, and disconnect, release and release complete messages, which are to release the call.
Next, the frame format used in ISDN will be described.
A transmission sequence number and a reception sequence number are affixed to an information frame. Each of these sequence numbers is incremented one by one when transmitted or received. Each of the transmission and reception sequence numbers is modulo (mod)
128
in which numerical values of 0 to 127 are repeatedly used (for example, 0, 1, 2, . . . 126, 127, 0, 1, 2, . . . ). For example, an information frame which is first transmitted is allotted with a transmission sequence number “0”, and an information frame which is secondly transmitted is allotted a transmission sequence number “1”. At this time, if the reception side has not yet received any information frame, the reception sequence number of an information frame transmitted by the reception side is equal to “0”. If the reception side receives an information frame, the reception sequence number of an information frame transmitted by the reception side is equal to “1”.
As the surveying frame, there are provided a reception ready (RR) frame for notifying the transmission sequence number of a frame to be next received (the number of frames which have been received) to a communication partner with which communications are being made when no information frames have been generated for a predetermined time period, and a reject (REJ) frame for detecting, on the basis of the transmission sequence number of the frame thus received, a frame which could not be received due to a transmission error, and requesting re-transmission of the missing frame. Like the information frame, a reception sequence number is also affixed to the surveying frame. In the case of the RR frame, it represents the transmission sequence number of a frame to be next received (the number of frames which have been received), and in the case of the REJ frame, it represents the transmission sequence number of a frame which could not be received due to a transmission error.
As the unnumbered frame, there are provided a set asynchronous balanced mode extended (SABME) frame, an unnumbered information (UI) frame, a disconnect (DISC) frame, an unnumbered acknowledgment (UA) frame, etc.
Next, a conventional communication system using ISDN will be described.
FIG. 12
is a schematic diagram showing a conventional communication system using ISDN.
As shown in
FIG. 12
, a communication terminal unit
503
is connected to ISDN
502
through DSU
504
. DSU
504
performs a control operation to physically connect the communication terminal unit
503
and ISDN
502
. The communication terminal unit
503
includes a rece
Denon Ltd.
Dickstein , Shapiro, Morin & Oshinsky, LLP
Olms Douglas
Sam Phirin
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