2 .\" Copyright (c) 1997, 1999 Hellmuth Michaelis. All rights reserved.
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25 .\" $Id: i4btel.4,v 1.9 1999/12/13 22:11:55 hm Exp $
27 .\" $FreeBSD: src/usr.sbin/i4b/man/i4btel.4,v 1.8.2.6 2003/03/13 03:10:59 trhodes Exp $
29 .\" last edit-date: [Mon Dec 13 23:13:39 1999]
36 .Nd isdn4bsd ISDN B-channel telephony interface driver
38 .Cd pseudo-device \&"i4btel\&" Op count
44 driver provides an interface to the B-channel for telephony applications
45 and is currently used by the
47 for answering machine support. The driver is part of the isdn4bsd package.
49 The lower six bits of the drivers's minor number is used to specify a
50 unit number, whereas the upper two bits specify a functionality.
52 Functionality zero is the usual telephony data stream i/o driver.
54 Functionality one is used to enable commands to dial out and hang up and
55 receive responses about the state of the dial out progress and status.
56 This commands may change in the future, for details see the file
62 The telephony data stream comes out of the line in a bit-reversed format,
65 driver does the bit-reversion process in any case.
67 Additionally, the user can specify to do A-law to u-law, u-law to A-law
68 or no conversion at all in the i4btel driver by using the
72 The driver is able to process several ioctl's:
74 .Bl -tag -width Ds -compact -offset indent
75 .It Ar I4B_TEL_GETAUDIOFMT
76 get currently used audio format conversion.
77 .It Ar I4B_TEL_SETAUDIOFMT
78 set currently used audio format conversion.
79 .It Ar I4B_TEL_EMPTYINPUTQUEUE
80 clear the input queue.
83 For the I4B_TEL_GETAUDIOFMT and I4B_TEL_SETAUDIOFMT, the following
84 parameters are available:
86 .Bl -tag -width Ds -compact -offset indent
88 do no A-law/u-law audio format conversion.
89 The conversion path looks like this:
91 USER <--> bitreversing <--> ISDN-line
94 set set audio format conversion to do an audio conversion from A-law
95 (on the ISDN line) to u-law (in the userland).
98 conversion path looks like this:
100 USER <-- u-law/A-law <-- bitreversing <-- ISDN-line
104 conversion path looks like this:
106 USER --> u-law/A-law --> bitreversing --> ISDN-line
109 set set audio format conversion to do an audio conversion from u-law
110 (on the ISDN line) to A-law (in the userland).
113 conversion path looks like this:
115 USER <-- A-law/u-law <-- bitreversing <-- ISDN-line
119 conversion path looks like this:
121 USER --> A-law/u-law --> bitreversing --> ISDN-line
125 A-Law and u-Law are specified in ITU Recommendation G.711.
135 device driver and this manpage were written by
136 .An Hellmuth Michaelis Aq hm@FreeBSD.org .