asterisk with ss7 via wanpipe, dahdi and libss7 – with isup sam support _ barryodonovan

5/24/2014 Asterisk with SS7 via Wanpipe, Dahdi and libss7 with ISUP SAM support | BarryODonovan.com

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Asterisk with SS7 via Wanpipe, Dahdi and libss7 with ISUP SAM supportPosted on January 12, 2012 by Barry O'Donovan

After much head banging in bringing up an SS7 link with SAM support, I am documented what worked here.

Firstly, what is SAM support? One end of an SS7 link initialises a new call by sending an Initial Address

Message (IAM). All SS7 software stacks support this and usually its enough. One case where its not enough is

when one wants to address a phone number with more than the E.164 standard max length of 16 (usually to

pass additional information tacked on the start, end of or even replacing an A or B number). In this scenario,

SS7 uses a Subsequent Address Message (SAM) to send the additional digits. Most / all mainstream Asterisk

SS7 software stacks do not support this.

The platform and software used is as follows:

Ubuntu 10.04 LTS standard CLI install;

dahdi-linux-complete-2.4.0 from the archives (direct link);

a patched version of libss7 supporting SAM via SVN (see below);

a patched version of chan-dahdi via SVN (see below);

Asterisk 1.6.0.28 from the archives (direct link);

Asterisk Addons 1.6.0.6 from the archives (direct link);

Sangoma Wanpipe 3.5.24 (direct link).

Yes, I know some of the above are obsolete. Unfortunately its whats required for everything to

play nicely together. And, guess what, it works!

Before You Start

Ensure you have all the necessary packages for building the packages:

apt-get install build-essential libnewt-dev subversion \

libsqlite3-dev libsnmp-dev bison libtool flex \

autoconf2.13 libmysqlclient-dev

You can assume the working directory is /usr/local/src in the following.

Installing dahdi-linux-complete

Download and extract dahdi-linux-complete into /usr/local/src. Then, in the same directory, create some

symbolic links:

ln -s dahdi-linux-complete-2.4.0+2.4.0/linux dahdi-linux

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ln -s dahdi-linux-complete-2.4.0+2.4.0/tools dahdi-tools

Now build dahdi-linux:

cd dahdi-linux

make

make install

Now move onto dahdi-tools:

cd dahdi-tools

./configure

make menuconfig # (and select tools or accept defaults)

make

make install

make config

Installing libss7

There is a patched version of Digiums libss7 referred to as Attilas libss7 available via SVN. Download and

install it:

svn co https://observer.router.hu/repos_pub/libss7/trunk alibss7

cd alibss7

make

make install

Installing Asterisk

Download and extract the Asterisk 1.6.0.28 package reference above.

cd asterisk-1.6.0.28

Now this next bit is very important and easy to miss - you also need a patched version of chan_dahdi.c

that is compatible with the patched version of libss7. This is also available from SVN:

svn co https://observer.router.hu/repos_pub/chan_dahdi/trunk achan_dahdi

Then copy it to your Asterisk source:

cp achan_dahdi/chan_dahdi.c asterisk-1.6.0.28/channels/chan_dahdi.c



Now continue with the Asterisk installation:

./configure

make menuconfig

make

make install

make samples

make config

Install Asterisk Addons (optional)

Download and unpack the above referenced add ons package and build and install:

cd asterisk-addons-1.6.0.6

./configure

make menuconfig

make

make install

make samples

Sangoma Wanpipe

Im using one of Sangomas E1 / T1 interface cards and so I need Wanpipe also. Im using version 3.5.24 and

preceed as follows after unpacking:

cd wanpipe-3.5.24./Setup install

During the install, follow these prompts:

select option 2 => Asterisk/Dahdi Support;

enter path /usr/local/src/dahdi-linux (for Zaptel path prompt);

select defaults for everything else;

you DO want to install start-up scripts;

you DO to configure wanpipe devices for DAHDI;

you DO want to generate /etc/asterisk/chan_dahdi.conf and:

select E1 / T1 as appropriate;

select line framing and encoding;

choose clock source;

select Zaptel/Dahdi PRI CPE as signalling;

select National ISDN 2 as switch type;

do not enable hardware DTMF detection;

use all channels;

select dial plan context as appropriate;

and continue for other ports as necessary;

finally, choose Save cfg: Stop Asterisk & Wanpipe now



you would like wanrouter to start on system boot;

and you would like to execute dahdi_cfg each time wanrouter starts.

Configuration Steps

We now need to set various options in Wanpipe, Dahdi and Asterisk for SS7 as its PRI/ISDN by default.

Edit all /etc/wanpipe/wanpipeX.conf files as necessary and change:

TDMV_DCHAN = 16

to

TDMV_DCHAN = 0

Now edit /etc/dahdi/system.conf and change (for example):

span=1,1,0,ccs,hdb3,crc4

bchan=1-15,17-31

echocanceller=mg2,1-15,17-31

hardhdlc=16

to

span=1,1,0,ccs,hdb3,crc4

bchan=2-31

echocanceller=mg2,2-31

mtp2=1

which of course assumes signalling is on channel 1. If you have voice only links, you might need something like:

span=1,0,0,ccs,hdb3,crc4bchan=1-31

echocanceller=mg2,2-31

Lastly, we need to configure Asterisk. Replace lines such as:

;Sangoma A102 port 1 [slot:4 bus:5 span:1]

switchtype=national

context=from-pstn

group=0

echocancel=yes

signalling=pri_cpe

channel =>1-15,17-31



with an appropriate configuration. Mine follows below with some edits and some important notes at the

end:

;Sangoma A102 port 1 [slot:4 bus:5 span:1]

switchtype=national

context=from-pstn

group=0

echocancel=yes

signaling=ss7

ss7type=itu

ss7_called_nai=dynamic

ss7_calling_nai=dynamic

ss7_internationalprefix=00

ss7_nationalprefix=0

ss7_subscriberprefix=

ss7_unknownprefix=

linkset=1

pointcode=1

adjpointcode=2

defaultdpc=3

networkindicator=national_spare

cicbeginswith=2

channel=2-31

sigchan=1

Set pointcode, adjpointcode and defaultdpc as appropriate;

set networkindicator as appropriate and ensure it matches the other end (you can see what youre being

sent and what youre sending via ss7 debug;

cicsbeginwith is normally 1 but the telco on my end are starting at 2 this was groping in the

dark diagnostics and issues such as no audio, CICs not in service when both sides claim they are, etc may

point to misaligned CICs;

make sure you have configured from-pstn or the appropriate context in yourextensions.conf.

Confirming Your Link Is Up

Now start wanrouter (/etc/init.d/wanrouter start); dahdi (/etc/init.d/dahdi start); and

Asterisk (/etc/init.d/asterisk start). You should see your link come up via logs available with

the dmesg command. Launch the Asterisk console and check the status of your links:

ast-deg1-1*CLI> ss7 show cics 1

CIC DPC DAHDI STATE BLOCKING

2 3 2 Idle

3 3 3 Idle

4 3 4 Idle

5 3 5 Idle

6 3 6 Idle

7 3 7 Idle

8 3 8 Idle

9 3 9 Idle

10 3 10 Idle

11 3 11 Idle



Share this:

Like this: Like

Be the f irst to like this.

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You should now be okay to make test calls.

Do You Need Professional Support / Consultancy?

While I will try to respond to comments and questions on this blog, I dont have the time to provide one on one

assistance pro-bono. Professional consultancy on Asterisk and SS7 is available worldwide through my

company, Open Solutions with contact details here.

References

For posterity, I have added Domjan Attila patched libss7 and chan_dahdi to GitHub:

https://github.com/barryo/attila-libss7

https://github.com/barryo/attila-libss7-chan_dahdi

This entry was posted in Links, Linux, My Links, OSS, Recipes, VoIP, Work and tagged asterisk, asterisk chan_ss7, chan_ss7, dahdi ss7, isup sam, libss7, linkedin, sam,

sangoma, sangoma ss7, ss7, ss7 sam, subsequent address message, zaptel ss7. Bookmark the permalink.

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