Download Documentation version 1.0 - Linux-Call-Router

Port
2: TE-mode BRI S/T interface line (for phone lines)
$
Connect an ISDN telephone as described above, and pick up the phone. You will not get a
dial tone from the kernel. In order to get a dial tone, the application LCR must be running.
But before running LCR, you must configure interfaces and “extensions”.
4.2 PBX lines
A PBX line, also known as point-to-point line, is only capable to connect one PBX (or one
telephone in point-to-point mode) to it. Also it features direct dialing in of extensions13. The
PBX, connected to this type of ISDN line, is able receive incoming calls, after the first digit
behind the main number is dialed. It is controlled by the PBX, when the number is complete.
It depends on the provider, how much digits can be dialed after the main number. The
international convention of the maximum length of a phone number is 13 digits. If the county
code has two digits (49 in Germany) and the area code has three digits (212 for the city
Solingen), and the main number has six digits, then there are two more digits that will be
routed to the PBX line. Of course the PBX can define by itself when the number is complete.
Inside Germany, more digits are allowed. The ‘German Telekom’ for example forwards up to
17 digits. The company, I work for, forwards up to 24 digits after the area code. The PBX will
signal, when the number is complete. This is supported by LCR.
Another advantage of a PBX line is the ability to have more than one ISDN line for the same
main number or prefix. One BRI ISDN line can handle two calls only at a time. The number
of simultaneous calls can be increased by heaving more than one line. LCR also supports this.
There is no know limit, except for the number of cards, that fit into your Linux box.
Note that PBX lines might get fault monitored by the telephone company, because they are
more expensive and more important than normal ISDN lines. In this case, talk to your
telephone company to ignore alarms because every reboot, crash or ever restarting of the LCR
or mISDN driver will cause alarms.
To tell mISDN to use a PBX line, you must set the card into point-to-point mode. This will
automatically done when using “genrc”. The protocol for the card driver would be 0x22.
(0x20 for PTP-mode, 0x02 for DSS1)
$ modproble fritzpci protocol=0x22 layermask=0xf debug=0x0
This will be included in the “mISDN” shell script, if the option “ptp” is selected when
running the “genrc” tool.
PBX lines may also be multipoint. You will be able to connect normal telephones to it. In
case of LCR it makes no difference. If telephones would be connected parallel to the PBX
line, dialing of extension digits will work until one phone on the bus is ringing.
Another type of PBX line is the PRI line or “primary rate multiplex” line. This type of line
provides 30 B-channels in Europe and 22 B-channels in the USA. It is used for really big
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DDI is a feature for incoming calls to dial an extension after the main prefix. The PBX will check the number
and signal, if it is complete.
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