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       ttyI - ISDN character devices with modem emulator


       ttyI[0-63]  are  emulated  tty  devices of the Linux ISDN subsystem.  These devices can be
       used in the same way as the traditional serial devices ttySx.  The official  major  device
       numbers are 43 for ttyI .  The minor device numbers start with 0 and end with 63.

       The ISDN tty devices are equipped with a modem emulation implementing a set of traditional
       and  some  special  AT  commands.  This  provides  easy  use  together  with  almost   all
       communication   software   that  uses  modem  commands:  minicom(1),  seyon(1),  XCept(1),
       uucico(8), mgetty(8), dip(8), pppd(8) and more. When enabled during kernel  configuration,
       the  emulator  is  capable  of  a  reduced  set of commands to support audio. To use audio
       features, an ISDN card with a audio-capable low-level driver is needed. Currently the only
       audio-capable drivers are the teles and HiSax driver.

       The  line  disciplines  are handled by the kernel so that SLIP, CSLIP and asynchronous PPP
       are possible.

       The port speed of the ISDN tty devices is always 64000 bps.


       The description of AT  commands  here  does  not  cover  audio  related  commands.  For  a
       description  of  audio related commands, see isdn_audio(4).  The following AT commands are
       supported by ISDN tty devices:

       ATA    Answer an incoming call.

       ATDnum Dial number num.  Allowed are digits [0-9] and the characters ",", "#",  ".",  "*",
              "W", "P", "T", "S", "-". The characters are ignored except of "S" which indicates a
              SPV if it precedes the number (only German 1TR6 ISDN).

       ATE0   Echo off.

       ATE1   Echo on (default).

       ATH    Hang up.

       ATH0   Hang up.

       ATH1   Off hook (ignored).

       ATI    Return device Information ("ISDN for Linux...").

       ATI0   Return device Information ("ISDN for Linux...").

       ATI1   Return device Information ("ISDN for Linux...").

       ATI2   Return Statistics of last connection.

       ATO    Return from command mode to online mode (data mode).

       ATQ0   Enable result codes (default).

       ATQ1   Disable result codes.

       ATSx=y Set register x to value y.

       ATSx?  Show content of register x.

              Set register x, bit y to value z

              Show bit y of register x.

       ATV0   Print result code as number.

       ATV1   Print result code as text (default).

       ATZ    Reset all registers and load profile values.

       AT&Bx  Set packet size of outgoing packets to value x (maximum 4000).  The  actual  packet
              size  depends on the hardware driver and may be smaller than x (e.g. with the teles
              driver). There will be no error message if the value is bigger  than  the  hardware
              driver can process. However the size of the outgoing packets will be set correctly.

       AT&D2  DTR falling edge: hang up and return to command mode (default).

       AT&D3  DTR falling edge: hang up, return to command mode and reset all registers.

       AT&Ex  Set  MSN  (Euro-ISDN,  EDSS1)  or  EAZ  (German 1TR6) to value x.  For MSNs, x is a
              string of digits representing the local phone number, while for EAZs  x  should  be
              only the last digit of the Number.

       AT&F   Set all registers and profile to "factory-defaults".

              Set  list  of  phone  numbers  to  listen on.  plist is a list of wildcard patterns
              separated by semicolon. If this is set, it has precedence over the MSN set by AT&E.

       AT&V   Show current register settings.

       AT&W0  Write registers and EAZ/MSN to profile. (You  need  to  run  iprofd(8)  for  making
              changes permanent.)

       AT&X0  Disable BTX-Mode (default).

       AT&X1  Enable BTX-Mode.


       During  a  data  connection,  the  driver  can  be  set  to  command  mode  by  typing  in
       delay+++delay.  The escape character (default "+") may be set via register  2.  The  delay
       must  be  at least 1.5 seconds and between each escape character the pause must not exceed
       0.5 seconds.  ATO brings the modem emulation back to data mode.


       0 (default 0)
              Number of rings  on  which  the  "modem"  will  answer.  (S0=0  will  disable  auto

       1 (default 0)
              Counts and stores the number of rings from an incoming call.

       2 (default 43 = '+')
              ASCII code of the escape character.

       3 (default 13 = CR)
              ASCII code of Carriage Return.

       4 (default 10 = LF)
              ASCII code of Line Feed.

       5 (default 8 = BS)
              ASCII code of Backspace.

       6 (default 3)
              Duration, in number of seconds, modem waits before dialling.

       7 (default 60)
              Wait time for carrier in seconds.

       8 (default 2)
              Pause time for comma (',') in dial command in seconds (ignored).

       9 (default 6)
              Carrier detect time in tenths of seconds (ignored).

       10 (default 7)
              Wait time until hangup after carrier loss in tenths of seconds (ignored).

       11 (default 70)
              Duration and delay in milliseconds for touch tone dialling (ignored).

       12 (default 69)
              Bit-mapped register.
              Bit  Description
              0    0 = Suppress response messages.
                   1 = Show response messages.
              1    0 = Response messages as text.
                   1 = Numeric response messages.
              2    0 = Echo off.
                   1 = Echo on.
              3    0 = DCD always on.
                   1 = DCD follows carrier.
              4    0 = CTS follows RTS.
                   1 = Ignore RTS, CTS always on.
              5    0 = Low-edge on DTR: Hangup and return
                        to command mode.
                   1 = Same as 0 but also resets all
              6    0 = DSR always on.
                   1 = DSR on only if channel is available.
              7    0 = Cisco-PPP-flag-hack off.
                   1 = Cisco-PPP-flag-hack on.

       13 (default 4)
              Bit-mapped register.
              Bit  Description
              0    0 = Use delayed sending of data.
                   1 = Immediately send data.
              1    0 = T.70 protocol off.
                   1 = T.70 protocol on.
              2    0 = Don't hangup on DTR low.
                   1 = Hangup on DTR low.
              3    0 = Standard response messages.
                   1 = Extended response messages.
              4    0 = CALLER NUMBER before every RING.
                   1 = CALLER NUMBER after first RING.
              5    0 = Disable extended T.70 protocol.
                   1 = Enable extended T.70 protocol.
              6    0 = Disable RUNG message.
                   1 = RUNG on cancelled incoming call.
              7    0 = Disable display messages from net.
                   1 = Enable disable messages from net.

       14 (default 0)
              Layer-2 protocol.
               0 = X75/LAPB with I-frames.
               1 = X75/LAPB with UI-frames.
               2 = X75/LAPB with BUI-frames.
               3 = HDLC.
               4 = TRANSPARENT.
              10 = Analog Modem. (only if hardware supports this)
              11 = Fax G3. (only if hardware supports this)

       15 (default 0)
              Layer-3 protocol.
              0 = transparent
              1 = transparent with audio features (e.g. DSP)
              2 = Fax G3

       16 (default 250)
              Outgoing packet size / 16.

       17     reserved.

       18 (default 4)
              Service-Octet-1 to accept or to be used on dial out.
              Bit-mapped register.
              Bit  Description
              0    Service 1 (audio) when set.
              1    Service 5 (BTX) when set.
              2    Service 7 (data) when set.

              Note: It is possible to set more than one bit. In this case, on outgoing calls, the
                     most significant 1-bit is chosen to select the outgoing  service  octet.  On
                     incoming  calls  the selected services are accepted, contents of register 14
                     is ignored and the Layer-2-protocol is automatically set with the  following
                     values to match the service of the incoming call:

                     Incoming service audio (Reg. 20.0 = 1)
                            L2-protocol is set to 4 (TRANSPARENT).

                     Incoming service BTX (Reg. 20.1 = 1)
                            L2-protocol is set to 0 (X75/LAPB with I-frames).

                     Incoming service date (Reg. 20.2 = 1)
                            L2-protocol is set to 0 (X75/LAPB with I-frames).

       19 (default 0)
              Service-Octet-2 (ignored when using EDSS1).

       20 (read only)
              Service-Octet-1  of last incoming call. This bit-mapped register is set on incoming
              call (during RING). Mapping is the same like register 18.

       21 (read only)
              Bit-mapped register. Set on incoming call (during RING) to the value of octet 3  of
              calling  party  number Information Element (Numbering plan).  See section 4.5.10 of
              ITU Q.931.

       22 (read only)
              Bit-mapped register. Set on incoming call (during RING) to the value of octet 3a of
              calling  party  number Information Element (Screening info).  See section 4.5.10 of
              ITU Q.931.

       23 (default 0)
              Bit-mapped register.
              Bit  Description
              0    0 = Disable CPN extended RING.
                   1 = Enable CPN extended RING.
              1    0 = Disable CPN extended FCON.
                   1 = Enable CPN extended FCON.

       NOTE   There used also be cui devices (major device number 44), but since the cua  devices
              for  regular  tty  devices are no longer supported in the kernel, these are also no
              longer supported for ISDN4linux.


       Fritz Elfert <>
       modified by Paul Slootman <>


       icnctrl(8), telesctrl(8), isdninfo(4), isdn_audio(4), isdnctrl(8).