Communication apparatus capable of communicating data and speech selectively through single communication line

A facsimile apparatus has a plurality of switching modes including a first mode to select facsimile communication or speech communication in accordance with a V.8 protocol signal and a second mode to select the facsimile communication or the speech communication in accordance with a call signal pattern and selects one of the switching modes to switch between the facsimile communication and the speech communication.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a communication apparatus capable of 
selectively communicating data and speech through a single communication 
line. 
2. Related Background Art 
A facsimile apparatus is known as an apparatus of this type. In a prior art 
facsimile apparatus, in order to selectively use a single telephone line 
for facsimile communication and speech communication, when a signal 
received from the line is a facsimile signal, it is determined that a 
sending station is a facsimile apparatus and the facsimile communication 
is started. Such an apparatus is described in U.S. Pat. No. 5,019,840 and 
U.S. Pat. No. 4,800,439. 
A service to allocate a plurality of telephone numbers to one telephone 
line and send out call signals corresponding to the respective telephone 
numbers (e.g. call signals having different cadences) by an exchange is 
known. A facsimile apparatus which utilizes this service while assigning a 
telephone number for speech communication and a telephone number for 
facsimile communication and identifying call signals for the facsimile 
apparatus to select the facsimile communication or the speech 
communication also is known. 
On the other hand, data communication between computers and image data 
communication by a facsimile apparatus have recently been conducted 
through a public telephone line and communication with various types of 
modems has been conducted. A modem for computer data communication and a 
modem for a facsimile apparatus are incompatible and cannot communicate 
with each other. Thus, where communication is to be conducted through a 
telephone line, it is required to identify the type of terminal of a 
destination station when a line is connected with the destination station, 
and a new communication is to be applied to achieve the communication. 
The prior art facsimile apparatus merely has independent functions to 
switch the facsimile communication and the speech communication and merely 
utilizes those functions independently. Thus, the facsmile apparatus may 
not properly switch the facsimile communication and the speech 
communication for the calls from various types of facsimile apparatus as 
above mentioned or telephone sets. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an improved 
communication apparatus. 
It is another object of the present invention to provide a communication 
apparatus capable of properly switching data communication and speech 
communication for a call from a communication apparatus having the new 
communication protocol described above. 
It is still another object of the present invention to provide a 
communication apparatus which has a plurality of switching modes including 
a first mode for selectively conducting the data communication and the 
speech communication in accordance with a type of call signal and a second 
mode for selectively switching the data communication and the speech 
communication by using the new communication protocol, and which selects 
an appropriate switching mode when it receives a call and selectively 
conducts the data communication and the speech communication in accordance 
with the selected switching mode to properly conduct the data 
communication and the speech communication. 
Other objects of the present invention will be apparent from the following 
detailed description of the preferred embodiments and the accompanying 
drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Embodiments of the present invention are now described in detail in 
conjunction with the drawings. In the following embodiments, a facsimile 
apparatus is illustrated and the V.8 protocol using a V.8 modem based of 
the ITU Recommendation V.8 is used as a new protocol for identifying a 
terminal attribute. In the V.8 protocol, as will be described in detail 
later, a protocol signal for identifying the terminal attribute is 
communicated. In the present embodiment, when it is determined by the 
protocol signal that the sending station is a telephone set, a 
communication line (telephone line) is connected to the telephone set for 
speech communication, and when it is determined that the sending station 
is a facsimile apparatus, facsimile communication is conducted. 
FIGS. 1A and 1B taken together forms a block diagram of a configuration of 
a facsimile apparatus of the present embodiment. 
A CML 2 is a relay for switching a telephone line to a facsimile 
communication unit and a telephone set. When a signal of a signal level 
`0` is outputted on a signal line 56a, a telephone line (signal lines 2a 
and 2b) is connected to the telephone set 6 (signal lines 10a and 10b), 
and when a signal of signal level `1` is outputted on the signal line 56a, 
the telephone line (the signal lines 2a and 2b) is connected to the 
facsimile communication unit (signal lines 16a and 16b). 
A TEL relay 4 is a relay for detecting non-ringing call reception and 
off-hook during communication. When a signal of signal level `0` is 
outputted on a signal line 56b, signal lines 6a and 6b are connected to 
signal lines 8a and 8b, and when a signal of signal level `1` is outputted 
on the signal line 56b, the signal lines 6a and 6b are connected to the 
signal lines 10a and 10b. When the signal of signal level `0` is outputted 
on the signal line 56b, an off-hook detection circuit 8 determines if the 
telephone set 6 is off hook off or not, and if it is off hook, a signal of 
signal level `1` is outputted to a signal line 8c, and if it is on hook, a 
signal of signal level `0` is outputted to the signal line 8c. 
A call signal detection circuit 10 receives the signals outputted on the 
signal lines 10a and 10b, and when it detects a call signal (ringing 
signal), it outputs a signal of signal level `1` on the signal line 10a, 
and when it does not detect the call signal, it outputs a signal of signal 
level `0` on the signal line 10a. 
A call signal pattern detection circuit 12 checks the detection signal for 
the call signal on the signal line 10a to detect a ringing pattern. When a 
standard ringing pattern (one on-state CI in one period) as shown in FIG. 
2A is detected, it outputs a signal `0` on the signal line 12a, and when a 
double ringing pattern (two on-state CI's in one period) as shown in FIG. 
2B is detected, it outputs a signal `1` on the signal line 12a, and when a 
triple ring pattern (short-short-long; three on-state CI's in one period) 
as shown in FIG. 2C is detected, it output a signal `2` on the signal line 
12a, and when a triple ring pattern (short-long-short; three on-state CI's 
in one period) as shown in FIG. 2D is detected, a signal `3` is outputted 
on the signal line 12a. 
A telephone number information detection circuit 14 detects telephone 
number information sent between call signals and outputs detected 
telephone number information to a signal line 14a. 
A hybrid circuit 16 separates a signal of a transmission unit and a signal 
of a receiving unit and sends a transmission signal from an adder circuit 
30 to the telephone line through the signal lines 16a, 16b and the CML 2, 
receives a signal from a sending station through the CML 2 and the signal 
lines 16a and 16b, and sends it to demodulators 32, 34, 36 and 38 through 
a signal line 16c. 
A V.21 modulator 18 modulates in accordance with the ITU-T Recommendation 
V.21. The modulator 18 modulates a protocol signal (signal line 56c) from 
a control unit 56 and sends the modulated signal to the adder circuit 30 
through a signal line 18a. 
A V.8 modulator 20 modulates in accordance with V.8 which is under 
discussion for recommendation. The modulator 20 receives the protocol 
signal on a signal line 56d, modulates the protocol signal and outputs the 
modulated data on a signal line 20a. 
A Q.PSK modulator 22 conducts a page-to-page protocol of image transmission 
in accordance with V.fast which is under discussion for recommendation. 
The modulator 22 receives a protocol signal on a signal line 56e, 
modulates the protocol signal and outputs the modulated data on a signal 
line 22a. 
A read circuit 24 sequentially reads one line of image signal along a main 
scan direction from a document sheet to be transmitted, generates a signal 
sequence representing binary, black and white values, and sends the data 
from a signal line 24a to an encoding circuit 26. The read circuit 24 
comprises an image pickup device such as a CCD (change coupled device) and 
an optical system. 
The encoding circuit 26 receives the read data outputted on the signal line 
24a, encodes the read data (MH, MR or MMR coding) and outputs the encoded 
data from a signal line 26a. 
A V.27ter, V.29, V.17 and V.34 modulator 28 receives the encoded data from 
the signal line 26a, modulates the encoded data in accordance with the 
known ITU-T Recommendation V.27ter (differential phase modulation), V.29 
(quadrature modulation), V.17 or V.35 which is under discussion for 
recommendation, and outputs the modulated data to the adder circuit 30 
through a signal line 28a. 
The adder circuit 30 receives signals on the signal lines 18a, 20a, 22a and 
28a and adds them. An output of the adder circuit 30 is sent to the hybrid 
circuit 16 from a signal line 30a. 
The V.21 demodulator 32 demodulates in accordance with the ITU-T 
Recommendation V.21. The demodulator 32 receives a protocol signal from 
the hybrid circuit 16 through the signal line 16c, demodulates the 
protocol signal in accordance with V.21 and sends the demodulated data to 
the control unit 56 through a signal line 32a. 
The V.8 demodulator 34 demodulates in accordance with V.8 which is under 
discussion for recommendation. The demodulator 34 receives the signal on 
the signal line 16c, demodulates the received signal in accordance with 
V.8 and outputs the demodulated data on a signal line 34a. 
The Q.PSK demodulator 36 conducts page-to-page protocol of image 
transmission in accordance with V.fast which is under discussion for 
recommendation. The demodulator 36 receives the signal on the signal line 
16c, demodulates the received signal in accordance with Q.PSK and outputs 
the demodulated data on the signal line 36a. 
The V.27ter, V.29, V.17 and V.34 demodulator 38 demodulates in accordance 
with the known ITU-T Recommendation V.27ter, V.29, V.17 or V.34 which is 
under discussion for recommendation. The demodulator 38 receives the 
modulated image signal from the hybrid circuit 16, demodulates the image 
signal and sends the demodulated data to a decoding circuit 40 through a 
signal line 38a. 
The decoding circuit 40 receives the information outputted on the signal 
line 38a and outputs decoded data (MH, MR or MMR decoding) to a recording 
circuit 42 through a signal line 40a. 
The recording circuit 42 receives the data outputted on the signal line 40a 
and sequentially records the received data one line at a time. 
A selection button 44 selects means (or more) by which it is determined 
whether the facsimile communication is to be conducted or the speech 
communication is to be conducted when a call is received. When the button 
44 is depressed, a depression pulse is generated on a signal line 44a. 
A display circuit 46 displays means by which it is determined whether the 
facsimile communication is to be conducted or the speech communication is 
to be conducted when the call is received. 
In the present embodiment, when a set pulse is generated on a signal line 
56g while the signal `0` is outputted on a signal line 56f, the means is 
determined by the ringing pattern of the call signal, and when the set 
pulse is generated on the signal line 56g while the signal `1` is 
outputted on the signal line 56f, the means is determined by the telephone 
number information between call signals, and when the set pulse is 
generated on the signal line 56g while the signal `2` is outputted on the 
signal line 56f, the means is determined by the sub-address information 
attribute information by the V.8 protocol signal. Each time the depression 
pulse is generated on the signal line 44a, the display is shifted one by 
one from "determination by call signal ringing pattern" to "determination 
by telephone number information between call signals" to "determination by 
sub-address information by a V.8 protocol signal". 
When the display circuit 46 displays "determination by call signal ringing 
pattern", it outputs the signal `0` on a signal line 46a, and when it 
displays "determination by telephone number information between call 
signals", it outputs the signal `1` on the signal line 46a, and when it 
displays "determination by sub-address information by V.8 protocol 
signal", it outputs the signal `2` on the signal line 46a. 
A registration button 48 is used to register a priority for means by which 
it is determined whether the facsimile communication is to be conducted or 
the speech communication is to be conducted when the call is received. 
When the button 48 is depressed, a depression pulse is generated on a 
signal line 48a. 
When a cursor key 50 is depressed, a depression pulse is generated on a 
signal line 50a. When a set key 52 is depressed, a depression pulse is 
generated on a signal line 52a. 
A register circuit 54 registers the priority selected by the button 48 and 
the keys 50, 52 through a signal line 54a. 
An operation unit or console unit 58 has a ten-key, one-touch dial keys, 
abbreviation dial keys and other function keys for registering in circuits 
60, 62 and 64 whether to conduct the facsimile communication or the speech 
communication when the call is received, correspondingly to the call 
signal ringing pattern (first mode), the telephone number between call 
signals (third mode) and the terminal attribute information or sub-address 
information by the V.8 protocol signal (second mode), respectively, and 
the depression information is outputted on a signal line 58a. 
The registration circuit 60 registers through a signal line 60a, when a 
fax/tel switching method (the first mode) to select the facsimile 
communication or the speech communication by the call signal ringing 
pattern is selected by the circuit 46 or 54, whether the facsimile 
communication is to be conducted or the speech communication is to be 
conducted in accordance with the four call signal ringing patterns when 
the call signal is received. 
The registration circuit 62 registers through a signal line 62a, when a 
fax/tel switching method (the third mode) for selecting the facsimile 
communication or the speech communication by the telephone number 
information between call signals is selected by the circuit 46 or 54, 
whether the facsimile communication is to be conducted or the speech 
communication is to be conducted in accordance with the telephone number 
information between call signals when the call signal is received. 
The registration circuit 64 registers through a signal line 64a, when a 
fax/tel switching method (the second mode) to select the facsimile 
communication mode or the speech communication mode by the attribute 
information or the sub-address information of the V.8 protocol signal is 
selected by the circuit 46 or 54, whether the facsimile communication is 
to be conducted or the speech communication is to be conducted in 
accordance with the sub-address information by the V.8 protocol signal 
when the call is received. 
The control unit 56 selects an appropriate switching mode from the 
above-mentioned plural switching modes when the call is received and 
controls the switching of the facsimile communication and the speech 
communication in accordance with the selected switching mode. The 
plurality of switching modes include the first mode by the call signal 
ringing pattern, the third mode by the telephone number information 
between call signals and the second mode by the V.8 protocol signal. 
FIGS. 3 to 5B are flow charts of a control operation of the control circuit 
56 in a first embodiment of the present invention. In the present 
embodiment, the circuits 48, 50, 52 and 54 are not used. 
In S72, a signal `0` is outputted on the signal line 56f and then a set 
pulse is outputted on the signal line 56g to display the determination by 
call signal ringing pattern on the display circuit 46 for the fax/tel 
switching method. 
In S74, a signal of signal level `0` is outputted on the signal line 56a to 
deactivate the CML relay 2. In S76, a signal of signal level `0` is 
outputted on the signal line 56b to deactivate the TEL relay 4. 
In S78, the information on the signal line 58a is received to determine 
whether the registration of the fax/tel switching by the call signal 
ringing pattern (the first mode, MODE 1) has been selected or not, and if 
it has been selected, the process proceeds to S80 to register in the 
circuit 60 whether the facsimile communication is to be conducted or the 
speech communication is to be conducted when the call is received in 
accordance with the four call signal ringing patterns, and if it has not 
been selected, the process proceeds to S82. 
In S82, the information on the signal line 58a is received to determine 
whether the registration of the fax/tel switching by the telephone number 
between call signals (the third mode, MODE 3) has been selected or not, 
and if it has been-selected, the process proceeds to S84 to register in 
the circuit 62 whether the facsimile communication is to be conducted or 
the speech communication is to be conducted when the call is received in 
accordance with the telephone number between call signals, and if it has 
not been selected, the process proceeds to S86. 
In S86, the information on the signal line 58a is received to determine 
whether the registration of the fax/tel switching by the attribute 
information or the sub-address information sent from the calling terminal 
device as the V.8 protocol signal (the second mode, MODE 2) has been 
selected or not, and if it has been selected, the process proceeds to S88 
to register in the circuit 64 whether the facsimile communication is to be 
conducted or the speech communication is to be conducted when the call is 
received in accordance with the attribute information or the sub-address 
information sent from the calling terminal device as the V.8 protocol 
signal, and if it has not been selected, the process proceeds to S90. 
In S90, the information outputted on the signal line 10a is received to 
determine whether the call signal has been detected or not, and if it has 
been detected, the process proceeds to S94, and if it has not been 
detected, the process proceeds to S92 to conduct other process. 
In S94, the signal on the signal line 46a is received and the information 
of the fax/tel switching method display circuit 46 is received to identify 
the selected fax/tel switching method. When the signal `0` is outputted on 
the signal line 46a, it means that the fax/tel switching is to be 
conducted by the call signal ringing pattern and the process proceeds to 
S96, and when the signal `1` is outputted on the signal line 46a, this 
means that the fax/tel switching is to be conducted by the telephone 
number information between call signals and the process proceeds to S108, 
and when the signal `2` is outputted on the signal line 46a, this means 
that the fax/tel switching is to be conducted by the sub-address 
information sent from the calling terminal device as the V.8 protocol 
signal and the process proceeds to S112. 
In S96, the information on the signal line 12a is received to recognize the 
call signal ringing pattern. In S98, the information on the circuit 60 is 
received to determine whether the detected call signal ringing pattern is 
for the facsimile communication or not, and if it is for the facsimile 
communication, the process proceeds to S100, and if it is for the speech 
communication, it proceeds to S104. 
In S100, a signal of signal level `1` is outputted on the signal line 56a 
to activate the CML relay 2, and in S102, the facsimile communication is 
conducted. Then, the process returns to S72. 
In S104, a signal of signal level `1` is outputted on the signal line 56b 
to activate the TEL relay 4, and in S106, the speech communication is 
conducted. Then, the process returns to S72. 
In S108, the telephone number information between call signals outputted on 
the signal line 14a is received to identify the telephone number between 
call signals. In S110, the information of the circuit 62 is received to 
determine whether the detected telephone number information between call 
signals is for the facsimile communication or the speech communication. If 
the information is for the facsimile communication, proceed to S100, and 
if the information is for the speech communication, proceed to S104. 
In S112, a signal of signal level `1` is outputted on the signal line 56a 
to activate the CML relay 2, and in S114, the pre-protocol by V.8 is 
conducted. The sub-address information attribute information sent from the 
calling terminal device is recognized. 
In S116, the information of the circuit 64 is received to determine whether 
the detected sub-address information by the V.8 protocol signal is for 
facsimile communication or not. When the information is for facsimile 
communication, the process proceeds to S118 to conduct facsimile 
communication and the process returns to S74. 
When the information is for speech communication, the process proceeds to 
S120 to call an operator by a circuit, not shown. The operator call may be 
stopped by the off-hook indication or the elapse of a predetermined time 
interval. 
In S122, a signal of signal level `1` is outputted on the signal line 56b 
to activate the TEL relay 4, and in S124, speech communication is 
conducted. When off-hook is detected, the CML relay 2 is activated. Then, 
the process returns to S74. 
A second embodiment of the present invention is now described. 
In the first embodiment, there is a case where the signal necessary for 
switching may not be detected when the call is received in the switching 
mode selected from a plurality (three) of switching modes. In the second 
embodiment, a priority to use the plurality (three) of switching modes is 
set in the circuit 54 and the facsimile apparatus is controlled in 
accordance with the use priority and the signal received when the call is 
received. In the present embodiment, the circuits 44 and 46 of FIG. 1B are 
not necessary. 
FIGS. 6 to 8B show portions of the operation of the second embodiment of 
the present invention which are different from that of the first 
embodiment. 
In FIGS. 6 to 8B, one of the first, second and third priority terminal 
information is sent. 
In the second embodiment, S73 of FIG. 3 is omitted. 
The process proceeds from S92 of FIG. 3 to S136 of FIG. 6. In S136, the 
information on the signal lines 48a, 50a and 52a are received to determine 
whether the registration of the priority for the fax/tel switching method 
has been selected or not. If it has been selected, the process proceeds to 
S138 to register the priority for the fax/tel switching at the reception 
of the call in the circuit 54, and if it has not been selected, the 
process proceeds to S74 of FIG. 3. 
The process proceeds from YES of S90 of FIG. 3 to S144 of FIG. 7A. In S144, 
the information of the circuit 54 is received to check the first priority 
for the fax/tel switching method. If the information is the sub-address 
information by the V.8 protocol signal, the process proceeds to S162. 
Otherwise, the process proceeds to S146. 
In S146, whether the first call signal priority ringing pattern or 
telephone number between call signals designated by the circuit 54 is 
present or not is determined. If it is present, the process proceeds to 
S148, and if it is not present, the process proceeds to S154. 
In S148, which is the first priority (YES of S146) or second priority (YES 
of S156) of the fax/tel switching method is determined, and if the method 
is the call signal ringing pattern, the process proceeds to S96 of FIG. 4, 
and if the method is the telephone number between call signals, the 
process proceeds to S108 of FIG. 5A. 
In S154, the information of the circuit 54 is received to check the second 
priority of the fax/tel switching method. If the information is the 
sub-address information by the V.8 protocol signal, the process proceeds 
to S186. Otherwise, the process proceeds to S156. 
In S156, whether the call signal ringing pattern or the telephone number 
between call signals designated as the second priority of the fax/tel 
switching method is present or not is determined. If the method is 
present, the process proceeds to S148, and if the method is not present, 
the process proceeds to S112 of FIG. 5B. 
In S162, a similar process to that of S112 and S114 of FIG. 5B is 
conducted. In S164, whether the attribute information or the sub-address 
information by the V.8 protocol signal has been detected or not is 
determined. If detected, the process proceeds to S116 of FIG. 5B, and if 
not detected, the process proceeds to S168. 
In S168, the information of the circuit 54 is received to check the second 
priority of the fax/tel switching method. If the information is the call 
signal ringing pattern, the process proceeds to S178, and if the 
information is the telephone number between call signals, the process 
proceeds to S170. 
In S170, whether the telephone number between call signals has been 
detected or not is determined. If detected, the process proceeds to S172, 
and if not detected, the process proceeds to S180. 
In S172, the telephone number detected by the signal line 14a is checked by 
the circuit 62. If the facsimile communication has been selected, the 
process proceeds to S102 of FIG. 4, and if the speech communication has 
been selected, the process proceeds to S120 of FIG. 5B. 
In S178, whether the call signal ringing pattern has been detected or not 
is determined. If detected, the process proceeds to S180, and if not 
detected, the process proceeds to S172. 
In S180, the detected call signal ringing pattern is checked by the circuit 
60. If the facsimile communication has been selected, the process proceeds 
to S102 of FIG. 4, and if the speech communication has been selected, the 
process proceeds to S120 of FIG. 5B. 
In S186, a similar process as that of S112 and S114 of FIG. 5B is 
conducted. In S188, whether the sub-address information attribute 
information has been detected in the V.8 pre-protocol or not is 
determined, and if the the sub-address information has been detected, the 
process proceeds to S116 of FIG. 5B, and if not detected, the process 
proceeds to S190. 
In S190, the information of the circuit 54 is received to check the third 
priority of the fax/tel switching method. If the information is the call 
signal ringing pattern, the process proceeds to S180, and if the 
information is the telephone number between call signals, the process 
proceeds to S172. 
In the registration circuit 64, for the fax, for example, the low order 
three bits (attribute information) of a call function of the V.8 CI 
(categories for indicator) signal and CM (categories for menu) signal are 
set to 001 or 101, and for the tel, the low order three bits of the call 
function of the V.8 CI signal and CM signal are set to 000. 
Specifically, in S116 of FIG. 5B, when the low order three bits of the call 
function of the CI signal and the CM signal are 001 or 101, the process 
proceeds to S118 to conduct the facsimile communication, and when the low 
order three bits of the call function of the CI signal and the CM signal 
are 000, the process proceeds to S120 to call the operator. 
Alternatively, in the registration circuit 64, for the fax for example, the 
low order three bits (sub-address information) of the terminal sub-address 
of the V.8 CI signal and CM signal are set to 000, and for the tel, the 
low order three bits of the terminal sub-address of the V.8 CI signal and 
CM signal are set to 001. 
Specifically, in S116 of FIG. 5B, when the low order three bits of the 
terminal sub-address of the CI signal and the CM signal are 000, the 
process proceeds to S118 to conduct the facsimile communication, and if 
the low order three bits of the terminal sub-address of the CI signal and 
the CM signal are 001, the process proceeds to S120 to call the operator. 
In the present embodiment, the call functions of the CI signal and the CM 
signal are of the same information and the terminal sub-addresses of the 
CI signal and the CM signal are of the same information. 
Contents of the V.8 signal and the call function signal are shown below. 
______________________________________ 
TABLE 1/V.8 Categories for indicator and menu sequences 
______________________________________ 
1 1111 1 111 1 Ten ONEs preamble to precede each 
sequence 
start 
Tag stop Information categories 
0 0000 0 000 1 Synchronization octet for CI AND AI 
sequences 
0 0000 0 111 1 Synchronization octet for CM and JM 
sequences 
0 1000 0 xxx 1 Call function indicating one of 8 call 
functions 
(se TABLE 1. callf/V.8) 
0 0100 0 xxx 1 Terminal sub-addressing 
0 1010 0 xxx 1 Modulation modes (see 
TABLE 1. modn/V.8) 
0 0101 0 xxx 1 Reserved by ITU-T for Protocols (eg 
T.30 or V.42) 
0 0011 0 xxx 1 Network interaction 
(eg G.164/G.165 disabling indicated 
in CI) 
______________________________________ 
(information categories not so far defined are all reserved for future us 
by the ITUT) 
______________________________________ 
TABLE 1.callf/V.8 The call function category 
______________________________________ 
start 
0 1000 Call function - octet `callf` 
0 indicates a tagged category octet and prevents flag 
simulation 
000 telephone (eg for return to voice) 
100 reserved by the ITU-T 
010 textphone 
110 reserved by the ITU-T 
001 transmit facsimile from the call terminal 
101 receive facsimile at the call terminal 
011 transmit and receive data 
111 as given by an extension octet 
1 stop bit 
______________________________________ 
As described hereinabove, the receiving station may conform the switching 
of the facsimile communication or the speech communication to that of the 
other facsimile apparatus in the network so that the proper switching of 
the facsimile communication and the speech communication is attained. 
When the other facsimile apparatus in the network cannot send the selected 
terminal identification with the first priority, the switching of the 
facsimile communication and the speech communication may be attained by 
the second or lower priority 
The present invention is not limited to the above embodiments, and various 
modifications thereof may be made without departing from the spirit and 
scope of the invention.