We can setup a test environment with chan_ss7 on a private SS7 test network, without the need for expensive SS7 test equipment.All we need is two machines 2 E1 cards, either digium/Sangoma and T1/PRI Crossover Cable. A normal call flow for a auto voice call to a mobile will be like as shown below.
Here the local server will inititate the call to the MSC(Mobile Switching Center), the MSC will route call to the subscriber depending upon the called number.
The E1 or LAN cable pin configuration for setting up the same locally is as below.
1 <—-> 4
2 <—-> 5
4 <—-> 1
5 <—-> 2
Now compile the drivers in the order dahdi,asterisk,chan_ss7,wanpipe if you are using sangoma card or dahdi,asterisk,chan_ss7 if you are using a digium card.Now make one server as master and other a slave . The master will serve as MSC(Mobile Switching Center) for us and the slave will be our Call initiating machine or the local machine .The configuration files for the Master machine and slave machine is below.Note the local machine OPC(Orgination Point code) will be master machine DPC(Destination Point code) and DPC will be master machines OPC.
Master machine (Which serve as an MSC)
system.conf
span=1,1,0,ccs,hdb3,crc4 bchan=1-15,17-31 mtp2=16
ss7.conf
[linkset-siuc] enabled => yes enable_st => no use_connect => yes hunting_policy => even_mru context => ss7 language => da subservice => auto
[link-l1] linkset => siuc channels => 1-15,17-31 schannel => 16 firstcic => 1 enabled => yes
[link-l2] linkset => siuc channels => 1-15,17-31 schannel => 16 firstcic => 1 enabled => yes
[host-test-server1] enabled => yes opc => 0x1 dpc => siuc:0x2 links => l1:1 [host-test-server2] enabled => yes opc => 0x2 dpc => siuc:0x1 links => l2:1
Slave machine configuration(Which serve as a call Initiation server)
system.conf
span=1,0,0,ccs,hdb3,crc4 bchan=1-15,17-31 mtp2=16
ss7.conf
[linkset-siuc] enabled => yes enable_st => no use_connect => yes hunting_policy => even_mru context => ss7 language => da subservice => auto
[link-l1] linkset => siuc channels => 1-15,17-31 schannel => 16 firstcic => 1 enabled => yes
[link-l2] linkset => siuc channels => 1-15,17-31 schannel => 16 firstcic => 1 enabled => yes
[host-test-server1] enabled => yes opc => 0x1 dpc => siuc:0x2
links => l1:1
[host-test-server2] enabled => yes opc => 0x2 dpc => siuc:0x1 links => l2:1
Start asterisk on both machines you can see GROUP RESET message coming and making the signaling link (16th time slot) INSERVICE and circuit idle.Configure a soft phone(Will act as a mobile for us).Make a callfile which initiate calls to the MSC from the localserver and we can see call terminating on the softphone.
The Master machine extensions.conf file should be like this.
[ss7]
exten => _X.,1,Dial(SIP/${EXTEN})
.
. At last tried an experiment by upgrading the ALSA driver and this time it got worked. Now i can hear sound in mic as well as in speakers…:).Anyone facing the same issue can give a try on this fix.
