isdn_audio(4)

1isdn_audio(4)                    Special files                   isdn_audio(4)
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NAME

6       isdn_audio - audio extension of ttyI ISDN character devices
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DESCRIPTION

9       This  document describes the audio related extensions of the modem emu‐
10       lation, provided by /dev/ttyIx.
11
12       The ISDN tty devices are equipped with a modem emulation implementing a
13       set of traditional and some special AT commands. This provides easy use
14       together with almost all communication software that  uses  modem  com‐
15       mands:  minicom(1),  seyon(1),  XCept(1), uucico(8), mgetty(8), dip(8),
16       pppd(8) and more. When enabled during kernel configuration, the  emula‐
17       tor  is  capable  of a reduced set of commands to support audio. To use
18       audio features, an ISDN card with a audio-capable low-level  driver  is
19       needed.  Currently  the  only  audio-capable  drivers are the teles and
20       HiSax driver.
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22       The port speed of the ISDN tty devices is always 64000 bps.
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24

AUDIO RELATED AT COMMAND SET

26       This description does not include the standard AT command  set.  For  a
27       description  of the standard AT command set, provided by the Linux ISDN
28       subsystem,  see  ttyI(4).   All  commands  starting  with  AT+   except
29       AT+FCLASS  are  enabled  only,  if audio mode is active.  The following
30       audio related AT commands are supported by ISDN tty devices:
31
32       AT+FCLASS=0
33              Disable audio mode (default). This command sets register  18  to
34              4.
35
36       AT+FCLASS=8
37              Enable audio mode. This command sets register 18 to 5.
38
39       AT+FCLASS=?
40              Show possible modes.
41
42       AT+FCLASS?
43              Show current mode.
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45       AT+VNH=x
46              No function, provided for compatibility only.
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48       AT+VNH=?
49              Always showing "1".
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51       AT+VNH?
52              Always showing "1".
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54       AT+VIP Reset all audio parameters.
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56       AT+VLS=x
57              Select line x, where x is one of the following:
58              0 = No device.
59              2 = Phone line.
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61       AT+VLS=?
62              Always showing "0,2".
63
64       AT+VLS?
65              Show current line.
66
67       AT+VRX Start audio recording. See below for more information.
68
69       AT+VSD=x,y
70              Set silence-detection parameters.
71              Possible parameters:
72              x = 0 ... 31  sensitivity threshold level.
73              (default 0 , deactivated)
74              y = 0 ... 255 range of interval in units of 0.1 second. (default
75              70)
76
77       AT+VSD=?
78              Show possible parameters.
79
80       AT+VSD?
81              Show current parameters.
82
83       AT+VSM=x
84              Select audio data format to x, where x is:
85              2 = ADPCM-2
86              3 = ADPCM-3
87              4 = ADPCM-4
88              5 = aLAW
89              6 = uLAW
90
91       AT+VSM=?
92              Show possible audio data formats.
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94       AT+VSM?
95              Show current audio data format.
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97       AT+VTX Start audio playback. See below for more information.
98

GENERAL BEHAVIOUR

100       On incoming calls, if the application responds to  a  RING  by  sending
101       ATA,  depending  on  the  calling  service,  the emulator responds with
102       either CONNECT (data call) or VCON (voice call).
103
104       When starting audio playback or recording, the emulator  responds  with
105       CONNECT.   After  that,  the data transfer  protocol described below is
106       used.  It is possible to initiate full duplex data transfer by  issuing
107       AT+VRX+VTX  in  a  single  command. In this case, no CONNECT message is
108       sent to the application and the protocol  described  below  is  started
109       immediately.
110
111       When  stopping audio playback or recording, the message returned by the
112       emulator depends on how the data  transfer  is  stopped.  If  the  data
113       transfer  is  stopped  by  a  remote  hangup, NO CARRIER is sent to the
114       application,  while  stopping  data  transfer  with  one  of  the   DLE
115       sequences,  VCON  is sent. In any case, the message is preceeded by the
116       appropriate DLE sequence for end of audio  data  and/or  abort  respec‐
117       tively.
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119       On  outgoing  voice calls, the emulator responds with VCON upon connec‐
120       tion setup.
121

AUDIO DATA FORMAT

123       When recording or playing back audio data, a kind  of  modified  bisync
124       protocol is used. When recording audio data, the modem emulator is con‐
125       sidered to be the sender, while the application is the receiver.   When
126       playing back, this relationship is reversed: The modem emulator acts as
127       receiver, while the application is the sender.  With the bisync  proto‐
128       col  the character DLE (0x10) has a special meaning and is used like an
129       escape character.  It is always followed by a  second  character  which
130       has the following meanings defined:
131
132       ETX (0x03)
133              End of audio data. This code has to be sent by the sender, indi‐
134              cating end of audio data.
135
136       DC4 (0x14)
137              Abort sending. This code has to be sent by the receiver, when it
138              wishes  to abort receiving data. The sender has to reply by stop
139              sending data and finally indicating end of audio data.
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141       DLE (0x10)
142              a single byte with value 0x10 in the data stream.
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144       0      Touch-tone "0" received. Valid only in direction  from  emulator
145              to application.
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147       1      Touch-tone  "1"  received. Valid only in direction from emulator
148              to application.
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150       2      Touch-tone "2" received. Valid only in direction  from  emulator
151              to application.
152
153       3      Touch-tone  "3"  received. Valid only in direction from emulator
154              to application.
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156       4      Touch-tone "4" received. Valid only in direction  from  emulator
157              to application.
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159       5      Touch-tone  "5"  received. Valid only in direction from emulator
160              to application.
161
162       6      Touch-tone "6" received. Valid only in direction  from  emulator
163              to application.
164
165       7      Touch-tone  "7"  received. Valid only in direction from emulator
166              to application.
167
168       8      Touch-tone "8" received. Valid only in direction  from  emulator
169              to application.
170
171       9      Touch-tone  "9"  received. Valid only in direction from emulator
172              to application.
173
174       #      Touch-tone "#" received. Valid only in direction  from  emulator
175              to application.
176
177       *      Touch-tone  "*"  received. Valid only in direction from emulator
178              to application.
179
180       A      Touch-tone "A" received. Valid only in direction  from  emulator
181              to application.
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183       B      Touch-tone  "B"  received. Valid only in direction from emulator
184              to application.
185
186       C      Touch-tone "C" received. Valid only in direction  from  emulator
187              to application.
188
189       D      Touch-tone  "D"  received. Valid only in direction from emulator
190              to application.
191

AUTHOR

193       Fritz Elfert <fritz@isdn4linux.de>
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NAME

DESCRIPTION

AUDIO RELATED AT COMMAND SET

GENERAL BEHAVIOUR

AUDIO DATA FORMAT

AUTHOR

SEE ALSO