Cellular Network Infrastructure

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***Please be aware that LCR is obsolete and osmo-sip-connector should be used istead.***

[[osmonitb:OsmoNITB LCR]] gives short setup and run OsmoNITB and LCR with Asterisk. 

This tutorial describes a similar approach to set up an [[OpenBSC:]] network-in-a-box with Asterisk.

Follow the instructions at [[Build from Source]] to build and install the following Osmocom projects:

* libosmocore

* libosmo-abis

* openbsc

lcr, mISDN and mISDNuser  source codes are available at http://git.misdn.org

You can use git client to download the source.

** LCR

<pre>

cd ../../lcr

ln -s ../libosmocore/ .

ln -s ../openbsc/openbsc/ .

sh autogen.sh

./configure --prefix=/usr --with-asterisk --with-gsm-bs

make

sudo make install

cp chan_lcr.so /usr/lib/asterisk/modules/

</pre>

On Debian 6 chan_lcr module will be loaded automatically on service restart, but in case it does not load

automatically, it is recommend adding the following line to your @/etc/modules.conf@

@load => chan_lcr.so@

** Configuring the system environment

<pre>

ldconfig

depmod –a

modprobe mISDN_core

modprobe mISDN_dsp

modprobe mISDN_l1loop nchannel=30 interfaces=2

</pre>

(Optional) Add following lines to your @/etc/modules@ file if you want your system to load the modules

automatically during boot

<pre>

mISDN_core

mISDN_dsp

mISDN_l1loop nchannel=30 interfaces=2

</pre>

* Configuring LCR

* Configuring GSM-BS

<pre>

cd /usr/etc/lcr

nano interface.conf

</pre>

Uncomment GSM section where it says ‘gsm-bs’. It is an interface for GSM Base Station, in this case,

osmo-nitb. Now LCR will connect to OpenBSC using its MNCC socket.

Add ‘bridge ast’ at the bottom of the GSM section. Now all calls from the GSM Base Station will be

forwarded to Asterisk.

** Set up chan_lcr

<pre>

[ast]

remote asterisk

context from-lcr

earlyb no

tones yes

bridge GSM

</pre>

LCR will connect to Asterisk using chan_lcr using context name ‘from-lcr’. Calls from Asterisk will be

forwarded to OpenBSC. The phone numbers defined in hlr.sqlite3 will be used to identify mobiles within

the network. Please refer to the example Asterisk configuration given below.

** Remove unnecessary interfaces

Comment the last two interfaces named Ext and Int. We do not need these interfaces. Now you have

chan_lcr and GSM Base Station interface bridged to each other. All calls from one interface will be

redirected to the other. No more routing configurations are necessary at this point.

** Set up permissions

<pre>

nano options.conf

</pre>

Uncomment the following 2 lines. LCR will not connect to chan_lcr if you do not set the user and group it

runs on.

<pre>

socketuser asterisk

socketgroup asterisk

</pre>

** Configuring Asterisk

Following is a simple example of asterisk dialplan that can be used to route all calls from OpenBSC back

to OpenBSC. But a few extensions listed in the default dialplan are accessible. Add the following lines to

your @/etc/asterisk/extensions.conf@

<pre>

[from-lcr]

include => default

exten => _X.,1,Dial(LCR/ast/${EXTEN:0},60)

</pre>

In this case, I am adding the default Asterisk dialplan. In Asterisk, default dialplan provides some features

to test drive your network. You can call 1234 for information on Asterisk, and 600 for latency test. Please

refer to the configuration file for more extensions. You might want to remove the default dialplan after

you confirm that the network is working properly