 |
Claims  |
|
|
What is claimed is:
1. A method for controlling a terminal equipment coupled to an intergrated
services digital network (ISDN) through a single communication line,
comprising the steps of:
discerning whether a message supplied from said ISDN is received, said
message being used at the time of setting up a call;
determining, each time said message is received, as to whether or not said
message includes information indicating whether a different terminal
equipment which said terminal equipment communicates with is a terminal
coupled to either an ISDN or an analog network other than said ISDN, said
analog network being coupled to said ISDN;
determining whether the different terminal equipment is a terminal coupled
to said ISDN or said analog network other than the ISDN by referring to
said information included in said message;
executing a first communication control suitable for exchanging data with
the different terminal equipment through said ISDN, when the different
terminal equipment is determined to be a terminal coupled to said ISDN by
referring to said information in said message; and
executing a second communication control suitable for exchanging data with
the different terminal equipment through said ISDN and said analog network
connected thereto, when the different terminal equipment is determined to
be a terminal coupled to said analog network other than said ISDN by
referring to said information included in said message.
2. A method for controlling a terminal equipment as claimed in claim 1,
wherein when said terminal equipment serves as a source terminal, said
message includes a call set-up accepted message indicating that a call
set-up message from said source terminal is accepted by the different
terminal equipment serving as a destination terminal, a call message
indicating that said destination terminal is being called, and an answer
message indicating that said destination terminal answers said call set-up
message.
3. A method for controlling a terminal equipment as claimed in claim 1,
wherein when said terminal equipment serves as a destination terminal,
said message includes a call set-up message received from the different
terminal equipment serving as a source terminal, and an answer
confirmation message supplied from said source terminal in response to an
answer message sent by said destination terminal.
4. A method for controlling a terminal equipment as claimed in claim 1,
wherein when all the messages used during the time when a call is set up,
do not have said information, the different terminal equipment is
determined to be a terminal coupled to the ISDN, and said first
communication control is executed.
5. A method for controlling a terminal equipment as claimed in claim 1,
wherein any one of said messages used during the time when a call is
set-up, has said information, the different terminal equipment is
determined to be a terminal coupled to said analog network, and said
second communication control is executed.
6. A method for controlling a terminal equipment as claimed in claim 1,
wherein said first communication control conforms to a group 4 facsimile
procedure as prescribed by CCITT recommendations.
7. A method for controlling a terminal equipment as claimed in claim 1,
wherein said second communication control conforms to a group 3 facsimile
procedure as prescribed by CCITT recommendations.
8. A method for controlling a terminal equipment as claimed in claim 1,
wherein said steps of discerning whether a message is received and
determining whether said message includes information are repetitively
carried out during a predetermined fixed time.
9. A terminal equipment coupled, through a single communication line, to an
integrated services digital network (ISDN) handling data in digital form,
comprising:
ISDN interface means, coupled to said ISDN, for executing a transmission
control procedure related to up to layer 3 of an ISDN structured
architecture.
discerning means for discerning whether a message supplied from said ISDN
is received through said ISDN interface means, said message being used at
the time of setting up a call;
first determining means, operatively coupled to said discerning means, for
determining, each time said message is received, as to whether or not said
message includes information on whether a different terminal equipment
which said terminal equipment communicates with is a terminal coupled to
either an ISDN or an analog network other than said ISDN, said analog
network being coupled to said ISDN;
second determining means, operatively coupled to said first determining
means, for determining whether the different terminal equipment is a
terminal coupled to said ISDN or said analog network other than the ISDN;
first control means, coupled to said second determining means, for
executing a first communication control suitable for exchanging data with
the different terminal equipment through said ISDN, when the different
terminal equipment is determined to be a terminal coupled to the ISDN by
referring to said information included in said message;
second control means, coupled to said second determining means, for
executing a second communication control suitable for exchanging data with
the different terminal equipment through said ISDN and said analog network
connected thereto, when the different terminal equipment is determined to
be a terminal coupled to said analog network other than said ISDN by
referring to said information included in said message; and
switching means for selectively connecting one of said first control means
and second control means to said ISDN interface means, said switching
means being controlled based on the determination result in said second
determining means.
10. A terminal equipment as claimed in claim 9, wherein normally, said
switching means selects said first control means.
11. A terminal equipment as claimed in claim 9, wherein normally, said
switching means selects said first control means, and selects said second
control means when the different terminal equipment is determined to be a
terminal coupled to said analog network other than said ISDN by said
second determining means.
12. A terminal equipment as claimed in claim 9, wherein said first
communication control conforms to a transport layer, a session layer, a
presentation layer and an application layer of said ISDN structured
architecture for a group 4 facsimile machine as prescribed by CCITT
recommendations.
13. A terminal equipment as claimed in claim 9, wherein said second control
means handles data in analog form and includes converting means for
converting said data in analog form into data in digital form which is
sent to said ISDN through said switching means and said ISDN interface
means and for converting data in digital form supplied from said ISDN
through said ISDN interface means and said switching means into data in
analog form.
14. A terminal equipment as claimed in claim 9, wherein when said terminal
equipment serves as a source terminal, said message includes a call set-up
accepted message indicating that a call set-up message from said source
terminal is accepted by the different terminal equipment serving as a
destination terminal, a call message indicating that said destination
terminal is being called, and an answer message indicating that said
destination terminal answers said call set-up message.
15. A terminal equipment as claimed in claim 9, wherein when said terminal
equipment serves as a destination terminal, said message includes a call
set-up message received from the different terminal serving as a source
terminal, and an answer confirmation message supplied from said source
terminal in response to an answer message sent by said destination
terminal.
16. A terminal equipment as claimed in claim 9, wherein when all the
messages used during the time when a call is set up, do not have said
information, the different terminal equipment is determined, by said
second determining means, to be a terminal coupled to the ISDN, and said
switching means selects said first control means.
17. A terminal equipment as claimed in claim 9, wherein any one of said
messages used during the time when a call is set-up, has said information,
the different terminal equipment is determined, by said second determining
means, to be a terminal coupled to said analog network and said switching
means selects said second control means.
18. A terminal equipment as claimed in claim 9, wherein said first
communication control conforms to a group 4 facsimile procedure as
prescribed by CCITT recommendations.
19. A terminal equipment as claimed in claim 9, wherein said second
communication control conforms to a group 3 facsimile procedure as
prescribed in CCITT recommendations.
20. A terminal equipment as claimed in claim 9, wherein said discerning
means and said first determining means operate during a predetermined
fixed time.
21. A terminal equipment as claimed in claim 9, further comprising storing
means for storing fee information supplied from said ISDN, calculating
means for calculating the sum total of fees from said fee information, and
output means for outputting said calculated sum total to an operator.
22. A terminal equipment as claimed in claim 21, further comprising input
means for inputting a period desired to calculate the sum total of fees,
wherein said calculating means calculates the sum total of fees related to
said input period. |
|
 |
|
 |
Claims |
|
|
|
Description |
|
|
BACKGROUND OF THE INVENTION
The present invention generally relates to a method for controlling a
terminal equipment coupled to an integrated services digital network and a
terminal equipment based on the same.
Recently, there has been considerable activity in the development of an
integrated services digital network (hereinafter simply referred to as an
ISDN). Currently, data terminal equipments for exchanging data with an
ISDN have been put to practical use. An ISDN will take place of a public
services telephone network (hereinafter simply referred to as a PSTN) in
the feature. However, both ISDN and PSTN will be used until the ISDN is
completely substituted for the PSTN. In order to construct a network
including both the ISDN and PSTN, internetworking has been proposed, which
enables it to be possible to exchange data between the ISDN and PSTN.
In the above-mentioned circumstance, a group 4 facsimile machine which uses
an ISDN as a transmission line is required to exchange data with a group 3
facsimile machine which uses a PSTN as a transmission line. In order to
meet this requirement, it is necessary to determine, prior to starting a
transmission control procedure for image information transmission, as to
whether a destination terminal is a group 4 facsimile machine coupled to
an ISDN or a group 3 facsimile machine coupled to a PSTN.
SUMMARY OF THE INVENTION
It is therefore a general object of the present invention to meet the
above-mentioned requirement.
A more specific object of the present invention is to provide a method for
controlling an ISDN terminal which can communicate with a terminal coupled
to a PSTN, and an ISDN terminal equipment based on the method.
The above objects of the present invention can be achieved a method for
controlling a terminal equipment coupled to an intergrated services
digital network (ISDN), comprising the steps of discerning whether a
message supplied from the ISDN is received, the message being used at the
time of setting up a call; determining, each time the message is received,
as to whether the message includes information on whether the other
terminal equipment to communicate with each other is a terminal coupled to
either an ISDN or an analog network other than the ISDN, the analog
network being coupled to the ISDN; determining whether the other terminal
equipment is a terminal coupled to the ISDN or an analog network other
than the ISDN by referring to the information included in the message;
executing a first communication control suitable for exchanging data with
the other terminal equipment through the ISDN, when the other terminal
equipment is determined to be a terminal coupled to the ISDN by referring
to the information included in the message; and executing a second
communication control suitable for exchanging data with the other terminal
equipment through the ISDN and the analog network connected thereto, when
the other terminal equipment is determined to be a terminal coupled to the
analog network other than the ISDN by referring to the information
included in the message.
The above-mentioned objects of the present invention can also be achieved
by a terminal equipment coupled to an integrated services digital network
(ISDN) handling data in digital form, comprising ISDN interface means,
coupled to the ISDN, for executing a transmission control procedure
related to up to layer 3 of an ISDN structured architecture; discerning
means for discerning whether a message supplied from the ISDN is received
through the ISDN interface means, the message being used at the time of
setting up a call; first determining means, coupled to the discerning
means, for determining, each time the message is received, as to whether
the message includes information on whether the other terminal equipment
to communicate with each other is a terminal coupled to either an ISDN or
an analog network other than the ISDN, the analog network being coupled to
the ISDN; second determining means, coupled to the first determining
means, for determining whether the other terminal equipment is a terminal
coupled to the ISDN or the analog network other than the ISDN; first
control means, coupled to the second determining means, for executing a
first communication control suitable for exchanging data with the other
terminal equipment through the ISDN, when the other terminal equipment is
determined to be a terminal coupled to the ISDN by referring to the
information included in the message; second control means, coupled to the
second determining means, for executing a second communication control
suitable for exchanging data with the other terminal equipment through the
ISDN and the analog network connected thereto, when the other terminal
equipment is determined to be a terminal coupled to the analog network
other than the ISDN by referring to the information included in the
message; and switching means for selectively connecting one of the first
control means and second control means to the ISDN interface means, the
switching means being controlled based on the determination result in the
second determining means.
Other objects, features and advantages of the present invention will become
apparent from the following detained description when read in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a preferred embodiment of the present
invention;
FIG. 2 is a plan view of an operation/display unit used in the embodiment;
FIG. 3 is a view illustrating a transmission procedure in an ISDN;
FIG. 3B is a view illustrating another transmission procedure;
FIG. 4 is a view illustrating internetworking between an ISDN and a PSTN;
FIG. 5A is a view illustrating a basic structure of a message related to
the layer 3;
FIG. 5B is a view illustrating a call set-up message information element;
FIG. 5C is a view illustrating a call set-up accepted message information
element;
FIG. 5D is a view illustrating a call message or an answer message;
FIG. 5E is a view illustrating a disconnection message or a release
message;
FIGS. 6A through 6D are flowcharts of a procedure executed at the time of
setting up a call;
FIGS. 7A and 7B are flowcharts of a procedure executing at the time of the
arrival of a call.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A description is given of a facsimile machine of a first preferred
embodiment of the present invention. FIG. 1 is a block diagram of the
first embodiment of the present invention. The illustrated facsimile
machine has a group 4 facsimile function, a group 3 facsimile function,
and a telephone set function.
A system controller 1 controls the entire facsimile machine. A parameter
memory 2 stores a variety of information inherent in the illustrated
facsimile machine, such as abbreviated dialing and fee information. A
scanner 3 reads a transmission document with a predetermined resolution
level. A plotter 4 prints an image with a predetermined resolution level.
An operation/display unit 5 is used for inputting data and displaying a
message, for example. A coder/decoder (CODEC) 6 compresses an image signal
by coding, and expands a compressed image signal by decoding so as to
generate the original image signal. The coder/decoder 6 has not only an
encoding function suitable for a group 3 facsimile machine but also an
encoding function suitable for a group 4 facsimile machine. An image
memory 7 is used for storing the compressed image data. A communication
controller 8 for a group 3 facsimile machine is used for controlling a
transmission procedure relating to a group 3 facsimile machine.
Hereinafter, the communication controller 8 is referred to as a G3
communication controller. A modem (modulator/demodulator) 9 has the
function of modulating and demodulating digital data. A handset 10 is made
up of a receiver (speaker) 10a and a transmitter (microphone) 10b.
An analog-to-digital converter (hereinafter simply referred to as an A/D
converter) 11 converts an analog signal supplied from the modem 9 or the
microphone 10b to a digital signal. An ISDN to which the illustrated
facsimile machine is coupled, processes a signal in digital form. A
digital-to-analog converter (hereinafter simply referred to as a D/A
converter )12 converts a digital signal supplied from the ISDN into an
analog signal. A communication controller 13 suitable for a group 4
facsimile machine is used for controlling a transmission procedure
relating to a group 4 facsimile machine. Hereinafter, the communication
controller 11 is referred to as a G4 communication controller. An ISDN
interface circuit 14 provides an ISDN line control related to up to layer
3. As is well known, a layer structure consisting of 7 layers, or an ISDN
structured architecture is recommended by CCITT (Comite Consultif
International Telegraphique et Telephonique). Layer 1 is a physical layer,
later 2 is a data link layer, and layer 3 is a network layer. Layer 4 is a
transport layer, layer 5 is a session layer, layer 6 is a presentation
layer, and layer 7 is an application layer.
A switch 15 connects a terminal side connection part of the ISDN interface
circuit 14 to any one of the A/D converter 11, the D/A converter 12 and
the G4 communication controller 13. A switch 16 connects an analog side
connection part of each of the A/D converter 11 and the D/A converter 12
to either the modem 9 or the handset 10.
The system controller 1, parameter memory 2, scanner 3, plotter 4,
operation/display unit 5, coder/decoder 6, image memory 7, G3
communication controller 8 and G4 communication controller 13 mutually
exchange data through a system bus 17. The ISDN interface circuit 14
exchanges a variety of information with the system controller 1 and the G4
communication controller 13. Normally, the switch 15 selects the G4
communication controller 13, and is switched so as to select the A/D
converter 11 and the D/A converter 12 when a destination terminal is
determined to be a G3 facsimile machine. Thereby, the transmission mode of
the facsimile machine is switched from the group 4 facsimile mode to the
group 3 facsimile mode, or the speech mode in which the handset 10 is
used.
On the other hand, normally, the switch 16 selects the handset 10. When an
operator takes off the handset 10, a hook switch (not shown) provided in
the handset 10 is switched to the offhook state. A signal indicative of
the state of the hook switch is applied to the system controller 1 through
a signal line indicated by a broken line. When the handset 10 is switched
to the offhook state, the system controller 1 controls the facsimile
machine so as to operate in the speech mode. In the speech mode, the
switch 15 is controlled so as to select the A/D converter 11 and D/A
converter 12. On the other hand, when the system controller 1 activates
the G3 communication controller 8 in order to provide the facsimile
function, the system controller 1 controls the switch 16 so as to select
the modem 9.
Referring to FIG. 2, there is illustrated the operation/display unit 5,
which has the following structural elements. A start key 5a is used for
starting a transmission operation and reception operation of the facsimile
machine. A stop key 5b is used for stopping the operation of the facsimile
machine. A ten key 5c is used for inputting numeric information such as a
telephone number and abbreviated dialing information. The ten key 5c has a
plurality of modes such as a telephone number input mode, a numeric data
input mode and a date input mode. A clear key 5d is used for cancelling
input information. A telephone key 5e sets the input mode of the ten key
5a to the telephone number input mode. A fee key 5f is used for
instructing the start of fee displaying. A liquid crystal pannel 5g is
used for displaying a variety of information on an operation guidance
message to the operator supplied from the facsimile machine, and the fee.
A description is given of a basic data transfer procedure of an ISDN
terminal equipment with reference to FIGS. 3A and 3B. Referring to FIG.
3A, a source terminal sends an ISDN a call set-up message SETUP in order
to request a call set-up to a destination terminal. Then the ISDN sends
the designated destination terminal the call set-up message SETUP in order
to call out the destination terminal. Further, the ISDN sends the source
terminal a call set-up accepted message CALL PROC in order to let the
source terminal know the call set-up state.
When the destination terminal detects the arrival of the call set-up
message SETUP, the destination terminal sends the ISDN a call message
ALERT which lets the source terminal know the start of ringing. When
destination terminal answers the call, it sends the ISDN an answer message
or connection message CONN. Correspondingly, the ISDN sends the source
terminal the answer message CONN to thereby let the source terminal know
that the destination terminal accepts the call.
The ISDN sends the destination terminal an answer confirmation message or a
connection acknowledgement CONN ACK. At this time, an information channel
for data transfer is established between the source and destination
terminals. Thereby, the source and destination terminals are allowed to
communicate with each other. After that, data transfer is carried out
between the source and destination terminals in accordance with respective
transfer control procedures. For example, data transfer based on the group
4 facsimile transfer control procedure is executed.
When the data transfer is completed, the source terminal sends the ISDN a
disconnection message DISC in order to request a release of the
information channel. The ISDN sends the destination terminal the
disconnection message DISC for letting the destination terminal know a
release of the information channel. Thereby, the destination terminal
sends back the ISDN a release message REL for letting the source terminal
know that the channel disconnection is completed. The ISDN sends the
source terminal the release message REL.
When the channel release is completed, the source terminal sends the ISDN a
release completion message REL COMP. Then, the ISDN sends the destination
terminal the release completion message REL COMP, and then the release of
the information channel is completed. Hence, the information channel
established between the source and destination terminals is completely
released from the connection state, and the line returns to the idle
state.
In this manner, the information channel is established between the source
and destination terminals, and is then released from the connection state.
Alternatively, it is possible for the destination terminal to send the
disconnect message DISC to thereby request a release of the information
channel from the connection state. In this case, messages illustrated in
FIG. 3B are sent.
The ISDN has the release message REL to be sent to the source terminal
include a fee information, when the information channel is released from
the used state and the disconnect message DISC has been sent from the
source terminal. Alternatively, when the disconnect message DISC is output
from the destination terminal, the ISDN has the release message REL to the
sent to the source terminal include a fee information.
Now, as shown in FIG. 4, a destination terminal TM2 can be coupled to an
ISDN by either a PSTN or, as shown in parenthesis, by an ISDN. If a
destination terminal TM2 which is coupled to an ISDN and designated by a
source terminal TMI at the time of setting up a call, is a data terminal
equipment coupled to a PSTN, the ISDN calls the designated destination
terminal TM2 by using an internetworking function. Thereby, an information
channel is established between the source terminal TMI coupled to the ISDN
and the destination terminal TM2 coupled to the PSTN. In this case, if the
functions of the source and destination terminals TMI and TM2 coincide
with each other, they can communicate with each other. At this time, the
ISDN lets the source terminal TMI coupled to the ISDN know that the
destination terminal is a non-ISDN terminal by adding a progress
identifier to various messages used for setting up a call, that is, the
call set-up accepted message CALL PROC, call message ALERT, answer message
CONN, and progress indication message PROG.
The above-mentioned messages in conformity to the layer 3 are described
below. As shown in FIG. 5A, each message consists of a protocol
identifier, a call number, a message type, an indispensable information
message, and an additional information message. The protocol identifier is
used for specifying the protocol specification (format and sequence) which
defines layer 3 call control messages. The call number is used for
specifying a call related to the present message. The message type
indicates the contents of the message. The indispensable information
message is added to each message without exception. The additional
information message is added to each message at need.
As shown in FIG. 5B, the call set-up message SETUP has a transmission
ability as an indispensable information element, and has, as additional
information elements, a progress identifier, a source number, a
destination number, low-level layer matching, and high-level layer
matching.
As shown in FIG. 5C, the call set-up accepted message CALL PROC includes
the channel identifier and the progress identifier, as additional
information elements. As shown in FIG. 5D, each of the call message CALL
and the answer message CONN includes the progress identifier, as an
additional element. The progress indication message PROG has the progress
identifier as an indispensable information element, and a reason
indication as an additional information element. As shown in FIG. 5E, each
of the disconnect message DISC and the release message REL includes the
reason indication as an indispensable element, and an indication as an
additional information element.
The contents of the information elements are described below. The
transmission ability defines an information transfer ability, a transfer
mode, an information transfer style, and information indicative of a
protocol of user's information. The information element of information
transfer ability represents the contents of the information to be
transmitted, by selecting any from among an audio, non-limited digital
information, limited digital information, 3.1 kHz audio, 7 kHz audio, and
video. The transfer mode indicates whether the exchange to be used for
data transfer is a line exchange or a packet exchange. The source number
represents the telephone number (ISDN address) of the source terminal, and
the destination number represents the telephone number of the destination
terminal.
The information element of the progress identifier indicates an event which
occurs during the time when a call is generated, such that a call is not
an ISDN end-to-end, the destination terminal is a non-ISDN terminal, or
the source terminal is a non-ISDN terminal.
The source number information element indicates an ISDN address (number) of
the source terminal, and the destination number information element
indicates the ISDN address of the destination terminal. The low-level
layer matching information element is used for checking whether or not it
is possible to communicate with the destination terminal, and basically
has the same contents as the information element related to the
transmission ability. Additionally, some detailed information may be
included in the low-level layer matching information element. The
high-level layer matching information element is used for checking whether
the source terminal matches the destination terminal, and indicates an
available terminal function such as a G2/G3 facsimile function, a G4
facsimile function, a mixed mode function, a teletex function, a videotex
function, a telex function, and a message handling system function.
The channel identifier information element is used for specifying a channel
or sub-channel used in the basic interface of an ISDN. The reason
indication information element is used for describing the reason why a
message is generated, a diagnosis message used when there is an error in
the procedure, and a source which generates the reason. The display
information element is used for displaying information required to be
displayed on a terminal, such as fee information.
It is noted that the source terminal knows that the destination terminal is
coupled to a network rather than an ISDN, such as a PSTN, from the
contents of the progress identifier, when this progress identifier is
included in at least one of the call set-up accepted message CALL PROC,
the call message ALERT, and the response message CONN, all of which are
sent from the ISDN, and/or when the progress identifier is included in the
progress indication message PROG. The source terminal determines that a
destination terminal is coupled to a network, such as PSTN, rather than an
ISDN, by performing various subroutines as shown in FIG. 6A-6D, for
example. In making this determination, as schematically shown in FIG. 1,
the system controller 1 performs a discerning subroutine 1a for discerning
whether a message supplied from the ISDN is received through the ISDN
interface, the message being used at the time of setting up a call. Then,
a first determining subroutine is performed for determining each time the
message is received, whether or not the message includes information on
whether a different terminal equipment to which the terminal equipment
communicates with is a terminal coupled to an ISDN or and analog network
other than an ISDN, the analog network being coupled to the ISDN.
Thereafter, as shown schematically in FIG. 1, the system controller 1
performs a second determining subroutine, 1c, for determining whether the
different terminal equipment is a terminal coupled to the ISDN or an
analog network other than the ISDN.
On the other hand, the source terminal knows that the source terminal is
coupled to a network rather than an ISDN, a PSTN, for example, from the
contents of the progress identifier, when this progress identifier is
included in the call set-up message SETUP supplied from the ISDN, and when
the progress indication message PROG.
Further, when the call set-up message SETUP includes the low-level layer
matching information element and the high-level layer matching information
element, the destination terminal can discern whether the source terminal
has the same function as itself from the contents of the above matching
information elements. Therefore, the destination terminal can determine
whether the call from the source terminal should be accepted or not from
the results.
In the above-mentioned manner, the source and destination terminal can
knows the available functions of the respective other terminals, prior to
starting data transfer.
A description is given of an operation of the facsimile machine shown in
FIG. 1 with reference to FIGS. 6A through 6D, which relate to the
procedure of selecting the transmission function to be used.
Referring to FIG. 6A, the system controller controls the ISDN interface
circuit 14 so as to send an ISDN the call set-up message SETUP (step 101).
Then the system controller 1 checks whether the call set-up accepted
message CALL PROC is received from the ISDN within a predetermined fixed
time (a NO loop related to steps 102 and 103). When the call set-up
accepted message CALL PROC is received and therefore the result in step
102 becomes YES, the system controller 1 of the source terminal discerns
whether or not the received call set-up accepted message CALL PROC
includes the progress identifier information element (step 104). When the
progress identifier information element is not included in the call set-up
accepted message CALL PROC and therefore the result in step 104 is NO, the
system controller 1 of the source terminal checks whether the call message
ALERT is received from the ISDN within a predetermined fixed time (a NO
loop related to steps 105 and 106). When the call message is received and
therefore the result in step 105 becomes YES, the system controller 1 of
the source terminal determines whether the received call message ALERT
includes the progress identifier information element (step 107). When the
result in step 107 is NO, the system controller 1 checks whether the
answer message CONN or the progress indication message PROG is received
within a predetermined fixed time from the reception of the call message
ALERT (a NO loop related to steps 108, 109 and 110).
When the answer message CONN is received and therefore the result in step
108 is YES, the system controller 1 of the source terminal discerns
whether or not the received answer message CONN includes the progress
identifier information element (step 111). When the result in step 111 is
NO, the destination terminal is an ISDN terminal and therefore, the system
controller 1 instructs the G4 communication controller 13 to start the
group G4 facsimile transmission control procedure (step 112). When the
progress indication message PROG is received and the result in step 109 is
YES, the system controller 1 discerns whether the received progress
message PROG includes the progress identifier information element (step
113). When the result in step 113 is NO, an error occurs in the contents
of the received progress indication message PROG. For this reason, the
system controller 1 instructs the ISDN interface circuit 14 to release the
information channel from the used state (step 114).
When the progress identifier information element is included in the call
set-up accepted message CALL PROC and the result in step 104 is YES, the
system controller 1 of the source terminal discerns whether the contents
of the progress identifier information element indicate that the
destination terminal is an non-limited ISDN terminal (step 115 of FIG.
6B). When the result in step 115 is NO, the procedure proceeds to step
105.
When the result in step 115 is yes, the system controller 1 sets the
facsimile machine to the group 3 facsimile mode (step 116). At this time,
the system controller 1 instructs the switch 15 to select the A/D
converter 11 and the D/A converter 12 so that they are connected to the
ISDN interface circuit 14. Further, the system controller 1 instructs the
switch 16 to the modem 9 so that the A/D converter 11 and D/A converter 12
are switched so as to be connected to the modem 9 from the handset 10.
After executing step 116, the system controller 1 discerns whether the call
message ALERT is received within a predetermined fixed time (a NO loop
related to steps 117 and 118). When the result in step 117 is YES, the
system controller discerns whether the answer message CONN is received
within a predetermined fixed time from the lapse of the predetermined
fixed time set in the NO loop related to steps 117 and 118 (a NO loop
related to steps 119 and 120). When the result in step 119 is YES, the
system controller 1 activates the G3 communication controller 8 so as to
start the group 3 facsimile transmission control procedure (step 121).
When the result in step 107 is YES, the system controller 1 of the source
terminal determines whether the contents of the progress identifier
information element indicate that the destination terminal is an non-ISDN
terminal (step 122 of FIG. 6C). When the result in step 122 is NO, the
procedure proceeds to step 108. Alternatively, when the result in step 122
is YES, the system controller 1 sets the facsimile machine to the group 3
facsimile mode as in the same way as in step 116 (step 123). Thereafter,
the procedure proceeds to step 119 shown in FIG. 6B.
When the result in step 111 is YES, the system controller 1 discerns
whether the contents of the progress identifier information element
indicate that the destination terminal is a non-ISDN terminal (step 124 of
FIG. 6D). When the result in step 124 is YES, the system controller 1 sets
the facsimile machine to the group 3 facsimile mode as in the same way as
in step 116 (step 125). Then the procedure proceeds to step 121.
During the time when the source terminal waits for any message, if a time
out occurs and therefore any one of the results in step 103, 106, 110, 118
and 120 becomes YES, the system controller 1 executes the in step 114 and
stops the information transfer.
In the above-mentioned manner, the source terminal is switched to the group
3 facsimile mode when the the received call set-up message SETUP includes
the progress identifier information element, and the contents thereof
indicate that the destination terminal is an non-ISDN terminal.
A description is given of an operation which is done when a call is
received, with reference to FIGS. 7A and 7B.
Referring to FIG. 7A, the system controller 1 waits for the reception of
the call set-up message SETUP from the ISDN (a NO loop related to step
201). When the call set-up message SETUP is received and therefore the
result in step 201 becomes YES, the system controller 1 of the destination
terminal discerns whether the progress identifier information element is
included in the received call set-up message SETUP (step 202). When the
result in step 202 is NO, the system controller 1 checks whether the
information transfer ability defined in the received call set-up message
SETUP indicates a non-limited digital signal with a bit rate of 64 kbps
(step 203). When the result in step 203 is YES, the system controller 1
determines whether the low-level layer matching information element is
included in the received call set-up message SETUP (step 204). Then the
result in step 204 is YES, the contents of the low-level layer matching
information element coincide with those of the own low-level layer
matching information stored in the parameter memory 2 (step 205). When the
result in step 205 is YES, the system controller 1 checks whether the
high-level layer matching information element is included in the received
call set-up message SETUP (step 206). When the result in step 206 is YES,
the system controller 1 discerns whether the contents of the included
high-level layer matching information element coincide with those of the
own high-level layer matching information stored in the parameter memory 2
(step 207). When the result in step 207 is YES, the system controller 1
instructs the ISDN interface circuit 14 to send the ISDN the answer
message CONN (step 208). After completing the send of the answer message
CONN, the system controller 1 monitors the reception of the answer
confirmation message CONN ACK within a predetermined fixed time (a NO loop
related to steps 209 and 210).
When the result in step 209 is YES, the system controller 1 instructs the
G4 communication controller 13 to start the group 4 facsimile transmission
control procedure (step 211). On the other hand, when the result in step
209 is negative, the system controller 1 instructs the ISDN interface
circuit 14 to disconnect the information channel (step 211), and returns
to the waiting state.
When the result in step 203 is NO, the system controller 1 checks whether
the information transfer ability included in the received call set-up
message SETUP indicates a 3.1 audio signal with a bit rate of 64 kbps
(step 213 shown in FIG. 7B). When the result in step 213 is YES, the
system controller 1 checks whether the low-level layer matching
information element is included in the received call set-up message SETUP
(step 214). When the result in step 204 is YES, the system controller 1
discerns whether the contents of the low-level layer matching information
element coincide with those of the own low-level layer matching
information stored in the parameter memory 2 (step 215). When the result
in step 215 is affirmative, the system controller 1 discerns whether the
high-level layer matching information element is included in the received
call set-up message SETUP (step 216). When the result in step 216 is YES,
the system controller 1 checks whether the contents of the high-level
layer matching information coincide with those of the own high-level layer
matching stored in the parameter memory 2 (step 217). When the result in
step 217 is YES, the destination terminal sends the ISDN the answer
message CONN (step 218), and then checks whether the answer confirmation
message CONN ACK is received within a predetermined fixed time from the
completion of sending the answer message CONN (a NO loop related to steps
219 and 220).
When the result in step 209 is YES, the system controller 1 instructs the
switch 15 to select the A/D converter 11 and the D/A converter 12 so that
the ISDN interface circuit 14 is switched so as to be connected to the A/D
converter 11 and the D/A converter 12 from the G4 communication controller
13. At the same time, the system controller 1 instructs the switch 16 to
select the modem 9 so that the facsimile machine is switched to the group
3 mode, and activates the G3 communication controller 8 so as to start the
group 3 facsimile transmission control procedure (step 221). On the other
hand, when the result in step 220 is YES, the the system controller 1
instructs the ISDN interface circuit 14 to disconnect the information
channel (step 222) and is switched to the waiting state.
On the other hand, the call-in is neglected, when the contents of the
low-level layer matching information ele | | |
