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134 lines
4.1 KiB
Groff
134 lines
4.1 KiB
Groff
.\"
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.\" Copyright (c) 1997, 2002 Hellmuth Michaelis. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.\" last edit-date: [Sun Jul 28 14:14:06 2002]
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.\"
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.Dd July 28, 2002
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.Dt I4BTEL 4
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.Os
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.Sh NAME
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.Nm i4btel
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.Nd isdn4bsd ISDN B-channel telephony interface driver
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.Sh SYNOPSIS
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.Cd device \&"i4btel\&" Op count
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.Sh DESCRIPTION
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The
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.Nm
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driver provides an interface to the ISDN B-channel for telephony applications
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and is currently used by the
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.Xr isdnd 8
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for answering machine support.
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The driver is part of the isdn4bsd package.
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.Pp
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The lower six bits of the drivers's minor number is used to specify a
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unit number, whereas the upper two bits specify a functionality.
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.Pp
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Functionality zero is the usual telephony data stream i/o driver.
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.Pp
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Functionality one is used to enable commands to dial out and hang up and
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receive responses about the state of the dial out progress and status.
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This commands may change in the future, for details see the file
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.Em i4b_tel_ioctl.h
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and the
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.Xr isdnphone 1
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utility.
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.Pp
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The telephony data stream comes out of the line in a bit-reversed format,
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so the
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.Nm
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driver does the bit-reversion process in any case.
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.Pp
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Additionally, the user can specify to do A-law to u-law, u-law to A-law
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or no conversion at all in the i4btel driver by using the
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.Xr isdntelctl 8
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utility.
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.Pp
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The driver is able to process several ioctl's:
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.Pp
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.Bl -tag -width Ds -compact -offset indent
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.It Ar I4B_TEL_GETAUDIOFMT
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get currently used audio format conversion.
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.It Ar I4B_TEL_SETAUDIOFMT
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set currently used audio format conversion.
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.It Ar I4B_TEL_EMPTYINPUTQUEUE
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clear the input queue.
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.El
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.Pp
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For the I4B_TEL_GETAUDIOFMT and I4B_TEL_SETAUDIOFMT, the following
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parameters are available:
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.Pp
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.Bl -tag -width Ds -compact -offset indent
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.It Ar CVT_NONE
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do no A-law/u-law audio format conversion.
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The conversion path looks like this:
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.Pp
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USER <--> bitreversing <--> ISDN-line
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.Pp
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.It Ar CVT_ALAW2ULAW
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set set audio format conversion to do an audio conversion from A-law
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(on the ISDN line) to u-law (in the userland).
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The
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.Xr read 2
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conversion path looks like this:
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.Pp
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USER <-- u-law/A-law <-- bitreversing <-- ISDN-line
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.Pp
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and the
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.Xr write 2
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conversion path looks like this:
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.Pp
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USER --> u-law/A-law --> bitreversing --> ISDN-line
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.Pp
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.It Ar CVT_ULAW2ALAW
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set set audio format conversion to do an audio conversion from u-law
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(on the ISDN line) to A-law (in the userland).
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The
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.Xr read 2
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conversion path looks like this:
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.Pp
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USER <-- A-law/u-law <-- bitreversing <-- ISDN-line
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.Pp
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and the
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.Xr write 2
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conversion path looks like this:
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.Pp
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USER --> A-law/u-law --> bitreversing --> ISDN-line
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.Pp
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.El
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.Sh STANDARDS
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A-Law and u-Law are specified in ITU Recommendation G.711.
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.Sh SEE ALSO
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.Xr g711conv 1 ,
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.Xr isdnphone 1 ,
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.Xr isdnd.rc 5 ,
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.Xr isdnd 8 ,
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.Xr isdntelctl 8
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.Sh AUTHORS
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The
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.Nm
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device driver and this manpage were written by
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.An Hellmuth Michaelis Aq hm@FreeBSD.org .
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