1The isdn diversion services are a supporting module working together with
2the isdn4linux and the HiSax module for passive cards. 
3Active cards, TAs and cards using a own or other driver than the HiSax 
4module need to be adapted to the HL<->LL interface described in a separate 
5document. The diversion services may be used with all cards supported by 
6the HiSax driver.
7The diversion kernel interface and controlling tool divertctrl were written
8by Werner Cornelius (werner@isdn4linux.de or werner@titro.de) under the
9GNU General Public License.
10
11    This program is free software; you can redistribute it and/or modify
12    it under the terms of the GNU General Public License as published by
13    the Free Software Foundation; either version 2 of the License, or
14    (at your option) any later version.
15
16    This program is distributed in the hope that it will be useful,
17    but WITHOUT ANY WARRANTY; without even the implied warranty of
18    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19    GNU General Public License for more details.
20
21    You should have received a copy of the GNU General Public License
22    along with this program; if not, write to the Free Software
23    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24
25Table of contents
26=================
27
281. Features of the i4l diversion services 
29   (Or what can the i4l diversion services do for me)
30
312. Required hard- and software
32
333. Compiling, installing and loading/unloading the module  
34   Tracing calling and diversion information 
35
364. Tracing calling and diversion information
37 
385. Format of the divert device ASCII output
39 
40
411. Features of the i4l diversion services 
42   (Or what can the i4l diversion services do for me)
43
44   The i4l diversion services offers call forwarding and logging normally 
45   only supported by isdn phones. Incoming calls may be diverted 
46   unconditionally (CFU), when not reachable (CFNR) or on busy condition 
47   (CFB). 
48   The diversions may be invoked statically in the providers exchange
49   as normally done by isdn phones. In this case all incoming calls
50   with a special (or all) service identifiers are forwarded if the 
51   forwarding reason is met. Activated static services may also be 
52   interrogated (queried).
53   The i4l diversion services additionally offers a dynamic version of
54   call forwarding which is not preprogrammed inside the providers exchange
55   but dynamically activated by i4l.
56   In this case all incoming calls are checked by rules that may be
57   compared to the mechanism of ipfwadm or ipchains. If a given rule matches
58   the checking process is finished and the rule matching will be applied
59   to the call.
60   The rules include primary and secondary service identifiers, called 
61   number and subaddress, callers number and subaddress and whether the rule
62   matches to all filtered calls or only those when all B-channel resources
63   are exhausted.
64   Actions that may be invoked by a rule are ignore, proceed, reject, 
65   direct divert or delayed divert of a call.
66   All incoming calls matching a rule except the ignore rule a reported and
67   logged as ASCII via the proc filesystem (/proc/net/isdn/divert). If proceed
68   is selected the call will be held in a proceeding state (without ringing)
69   for a certain amount of time to let an external program or client decide
70   how to handle the call. 
71            
72
732. Required hard- and software
74   
75   For using the i4l diversion services the isdn line must be of a EURO/DSS1
76   type. Additionally the i4l services only work together with the HiSax 
77   driver for passive isdn cards. All HiSax supported cards may be used for
78   the diversion purposes.
79   The static diversion services require the provider having static services
80   CFU, CFNR, CFB activated on an MSN-line. The static services may not be 
81   used on a point-to-point connection. Further the static services are only
82   available in some countries (for example germany). Countries requiring the 
83   keypad protocol for activating static diversions (like the netherlands) are
84   not supported but may use the tty devices for this purpose.
85   The dynamic diversion services may be used in all countries if the provider
86   enables the feature CF (call forwarding). This should work on both MSN- and
87   point-to-point lines.
88   To add and delete rules the additional divertctrl program is needed. This
89   program is part of the isdn4kutils package.   
90
913. Compiling, installing and loading/unloading the module  
92   Tracing calling and diversion information 
93
94
95   To compile the i4l code with diversion support you need to say yes to the 
96   DSS1 diversion services when selecting the i4l options in the kernel 
97   config (menuconfig or config).
98   After having properly activated a make modules and make modules_install all
99   required modules will be correctly installed in the needed modules dirs.
100   As the diversion services are currently not included in the scripts of most
101   standard distributions you will have to add a "insmod dss1_divert" after
102   having loaded the global isdn module.
103   The module can be loaded without any command line parameters.
104   If the module is actually loaded and active may be checked with a 
105   "cat /proc/modules" or "ls /proc/net/isdn/divert". The divert file is 
106   dynamically created by the diversion module and removed when the module is
107   unloaded.
108
109
1104. Tracing calling and diversion information
111 
112   You also may put a "cat /proc/net/isdn/divert" in the background with the
113   output redirected to a file. Then all actions of the module are logged.
114   The divert file in the proc system may be opened more than once, so in 
115   conjunction with inetd and a small remote client on other machines inside
116   your network incoming calls and reactions by the module may be shown on 
117   every listening machine. 
118   If a call is reported as proceeding an external program or client may 
119   specify during a certain amount of time (normally 4 to 10 seconds) what
120   to do with that call.      
121   To unload the module all open files to the device in the proc system must
122   be closed. Otherwise the module (and isdn.o) may not be unloaded. 
123
1245. Format of the divert device ASCII output
125 
126   To be done later
127
128