VoLTE Setup with Kamailio IMS and Open5GS Open Source

Open5GS

VoLTE Setup with Kamailio IMS and Open5GS

2023-07-19 03:22

Setup description:

  • MCC: 001, MNC: 01
  • Single OpenStack VM with Kamailio IMS and Open5GS (Internal IP 10.4.128.21 and Floating IP 172.24.15.30)
  • 4G Casa Smallcell
  • Sysmocom USIM – sysmoUSIM-SJS1
  • Oneplus 5 as UE

OpenStack is not required for VoLTE setup. If you are using one machine without OpenStack, you can start from step 3.

1. Start from Bionic Ubuntu cloud image

2. Use the following Cloud init config while spawning an instance

#cloud-config
disable_root: 0
ssh_pwauth: True
users:
  - name: root
chpasswd:
  list: |
    root:admin
  expire: False
runcmd:
  - sed -i -e '/^#PermitRootLogin/s/^.*$/PermitRootLogin yes/' /etc/ssh/sshd_config
  - systemctl restart sshd

This removes all existing cloud users and allows only root user and sets a password

3. Install following packages

$ apt update && apt upgrade -y && apt install -y mysql-server tcpdump screen ntp ntpdate git-core dkms gcc flex bison libmysqlclient-dev make \
libssl-dev libcurl4-openssl-dev libxml2-dev libpcre3-dev bash-completion g++ autoconf rtpproxy libmnl-dev libsctp-dev ipsec-tools libradcli-dev \
libradcli4

4. Clone Kamailio repository and checkout 5.3 version of repository

$ mkdir -p /usr/local/src/
$ cd /usr/local/src/
$ git clone https://github.com/herlesupreeth/kamailio
$ cd kamailio
$ git checkout -b 5.3 origin/5.3

5. Generate build config files

$ cd /usr/local/src/kamailio
$ make cfg

6. Enable MySQL module and all required IMS modules.

Edit modules.lst file present at /usr/local/src/kamailio/src

The contents of modules.lst should be as follows:

# this file is autogenerated by make modules-cfg

# the list of sub-directories with modules
modules_dirs:=modules

# the list of module groups to compile
cfg_group_include=

# the list of extra modules to compile
include_modules= cdp cdp_avp db_mysql dialplan ims_auth ims_charging ims_dialog ims_diameter_server ims_icscf ims_ipsec_pcscf ims_isc ims_ocs ims_qos ims_registrar_pcscf ims_registrar_scscf ims_usrloc_pcscf ims_usrloc_scscf outbound presence presence_conference presence_dialoginfo presence_mwi presence_profile presence_reginfo presence_xml pua pua_bla pua_dialoginfo pua_reginfo pua_rpc pua_usrloc pua_xmpp sctp tls utils xcap_client xcap_server xmlops xmlrpc

# the list of static modules
static_modules=

# the list of modules to skip from compile list
skip_modules=

# the list of modules to exclude from compile list
exclude_modules= acc_json acc_radius app_java app_lua app_lua_sr app_mono app_perl app_python app_python3 app_ruby auth_ephemeral auth_identity auth_radius cnxcc cplc crypto db2_ldap db_berkeley db_cassandra db_mongodb db_oracle db_perlvdb db_postgres db_redis db_sqlite db_unixodbc dnssec erlang evapi geoip geoip2 gzcompress h350 http_async_client http_client jansson janssonrpcc json jsonrpcc kafka kazoo lcr ldap log_systemd lost memcached misc_radius ndb_cassandra ndb_mongodb ndb_redis nsq osp peering phonenum pua_json rabbitmq regex rls rtp_media_server snmpstats systemdops topos_redis uuid websocket xhttp_pi xmpp $(skip_modules)

modules_all= $(filter-out modules/CVS,$(wildcard modules/*))
modules_noinc= $(filter-out $(addprefix modules/, $(exclude_modules) $(static_modules)), $(modules_all)) 
modules= $(filter-out $(modules_noinc), $(addprefix modules/, $(include_modules) )) $(modules_noinc) 
modules_configured:=1

7. Compile and install Kamailio

$ cd /usr/local/src/kamailio
$ export RADCLI=1
$ make Q=0 all | tee make_all.txt
$ make install | tee make_install.txt
$ ldconfig

The binaries and executable scripts are installed in: /usr/local/sbin

kamailio - Kamailio SIP server
kamdbctl - script to create and manage the Databases
kamctl - script to manage and control Kamailio SIP server
kamcmd - CLI - command line tool to interface with Kamailio SIP server

To be able to use the binaries from command line, make sure that /usr/local/sbin is set in PATH environment variable. You can check that with echo $PATH. If not and you are using bash, open /root/.bash_profile and at the end add:

  PATH=$PATH:/usr/local/sbin
  export PATH

Kamailio modules are installed at: /usr/local/lib64/kamailio/modules

The documentation and readme files are installed at: /usr/local/share/doc/kamailio

The configuration files are installed at: /usr/local/etc/kamailio

In case you set the PREFIX variable in make cfg command, then replace /usr/local in all paths above with the value of PREFIX in order to locate the files installed.

8. Populate MySQL database using kamctlrc command

Edit SIP_DOMAIN and DBENGINE in the /usr/local/etc/kamailio/kamctlrc configuration file (Used by kamctl and kamdbctl tools).

Set the SIP_DOMAIN to your SIP service domain (or IP address if you don’t have a DNS hostname associated with your SIP service). Set the DBENGINE to be MYSQL and adjust other setting as you want. Finally, uncomment both SIP_DOMAIN and DBENGINE.

In example above, the following values are set for SIP_DOMAIN and DBENGINE

SIP_DOMAIN=ims.mnc001.mcc001.3gppnetwork.org
DBENGINE=MYSQL

You can change other values in kamctlrc file. Once you are done updating kamctlrc file, run the script to create the database used by Kamailio:

$ kamdbctl create

When prompted for mysql root user password enter the root password if its is set or else leave it blank i.e. Press Enter

check database manually;

$ mysql
<mysql> show databases;
<mysql> use kamailio;
<mysql> show tables;
<mysql> select * from subscriber;

No Subscribers are added yet

The kamdbctl will add two users in MySQL user tables:

- kamailio   - (with default password 'kamailiorw') - user which has full access rights to 'kamailio' database
- kamailioro - (with default password 'kamailioro') - user which has read-only access rights to 'kamailio' database

9. Edit /etc/default/rtpproxy file as follows:

# Defaults for rtpproxy

# The control socket.
#CONTROL_SOCK="unix:/var/run/rtpproxy/rtpproxy.sock"
# To listen on an UDP socket, uncomment this line:
#CONTROL_SOCK=udp:127.0.0.1:22222
CONTROL_SOCK=udp:127.0.0.1:7722

# Additional options that are passed to the daemon.
EXTRA_OPTS="-l 172.24.15.30 -d DBUG:LOG_LOCAL0"

here, -l <PUBLIC_IP>

Then run,

$ systemctl restart rtpproxy

10. Edit configuration file to fit your requirements for the VoIP platform:

You have to edit the /usr/local/etc/kamailio/kamailio.cfg configuration file.

Follow the instruction in the comments to enable usage of MySQL. Basically you have to add several lines at the top of config file, like:

#!define WITH_MYSQL
#!define WITH_AUTH
#!define WITH_USRLOCDB
#!define WITH_NAT

(uncomment this line)
auto_aliases=no

(uncomment this line and enter the DNS domain created above)
alias="ims.mnc001.mcc001.3gppnetwork.org"

(uncomment this line, 10.4.128.21 is the internal IP and 172.24.15.30 is the Public/Floating IP)
listen=udp:10.4.128.21:5060 advertise 172.24.15.30:5060
listen=tcp:10.4.128.21:5060 advertise 172.24.15.30:5060

(Further down, we will need to modify the rtpproxy_sock value to match the CONTROL_SOCK option we set for RTPProxy in /etc/default/rtpproxy)
modparam("rtpproxy", "rtpproxy_sock", "udp:127.0.0.1:7722")

If you changed the password for the ‘kamailio’ user of MySQL, you have to update the value for ‘DBURL’ parameters.

11. The init.d script

The init.d script can be used to start/stop the Kamailio server in a nicer way. A sample of init.d script for Kamailio is provided at:

/usr/local/src/kamailio/pkg/kamailio/deb/debian/kamailio.init

Just copy the init file into the /etc/init.d/kamailio. Then change the permissions:

$ cp /usr/local/src/kamailio/pkg/kamailio/deb/bionic/kamailio.init /etc/init.d/kamailio
$ chmod 755 /etc/init.d/kamailio

Then edit the /etc/init.d/kamailio file updating the $DAEMON and $CFGFILE values:

PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin
DAEMON=/usr/local/sbin/kamailio
CFGFILE=/usr/local/etc/kamailio/kamailio.cfg

You need to setup a configuration file in the /etc/default/ directory. This file can be found at:

/usr/local/src/kamailio/pkg/kamailio/deb/bionic/kamailio.default

You need to rename the /etc/default/kamailio file to ‘kamailio’ after you’ve copied it. Then edit this file and set RUN_KAMAILIO=yes. Edit the other options as per your setup.

$ cp /usr/local/src/kamailio/pkg/kamailio/deb/bionic/kamailio.default /etc/default/kamailio
$ systemctl daemon-reload

Create the directory for pid file:

$ mkdir -p /var/run/kamailio

Default setting is to run Kamailio as user kamailio and group kamailio. For that you need to create the user and set ownership

$ adduser --quiet --system --group --disabled-password \
        --shell /bin/false --gecos "Kamailio" \
        --home /var/run/kamailio kamailio
$ chown kamailio:kamailio /var/run/kamailio

Then you can start Kamailio using the following commands:

$ systemctl start kamailio.service
check running processes with: ps axwegrep kamailio

12. A quick check for the basic working of SIP server can be done as follows:

Create new subscriber accounts. A new account can be added using kamctl tool via kamctl add <username> <password> (When asked for entering MySQL password for user kamailio@localhost: type kamailiorw, as provided in kamailio.cfg)

$ kamctl add test testpasswd
$ kamctl add test2 testpasswd

Setting on OnePlus phones

  • Connect to a network through which SIP server is reachable (either Wi-Fi or LTE)
  • Goto phone dialer and select the Settings in the menu on top right corner
  • Then select Call settings
  • Configure SIP accounts in phones as added above using kamctl:

In Phone 1:

Username: test
Password: testpasswd
Server: ims.mnc001.mcc001.3gppnetwork.org (Created DNS Domain Name or IP to which IMS components are bound to, visible interface IP address)
Optional Settings:
    Authentication username: test
    Outbound proxy address: 172.24.15.30 (Floating IP of VM in case of OpenStack or else no need to fill in case of physical machine)
    Transport type: UDP

In Phone 2:

Username: test2
Password: testpasswd
Server: ims.mnc001.mcc001.3gppnetwork.org (Created DNS Domain Name or IP to which IMS components are bound to, visible interface IP address)
Optional Settings:
    Authentication username: test2
    Outbound proxy address: 172.24.15.30 (Floating IP of VM in case of OpenStack or else no need to fill in case of physical machine)
    Transport type: UDP
  • Set “Receive incoming calls” option to enabled state in both phones
  • Set “Use SIP calling” to “For all calls”
  • Add a new contact as follows:

In Phone 1:

Select more option

Name: SIP Contact test2 (Any arbitary name)
SIP: test2@ims.mnc001.mcc001.3gppnetwork.org (Created DNS Domain Name or IP to which IMS components are bound to, visible interface IP address)

Save and exit

In Phone 2:

Select more option

Name: SIP Contact test (Any arbitary name)
SIP: test@ims.mnc001.mcc001.3gppnetwork.org (Created DNS Domain Name or IP to which IMS components are bound to, visible interface IP address)

Save and exit

  • Now try calling from either phone

Upon completion of this test, set “Receive incoming calls” option to disabled state and set “Use SIP calling” to “Only for SIP calls”

13. Create new mysql database for pcscf, scscf and icscf, populate databases and grant permissions to respective users identified by a password

$ mysql
<mysql> CREATE DATABASE  `pcscf`;
<mysl> CREATE DATABASE  `scscf`;
<mysl> CREATE DATABASE  `icscf`;

In all of the below steps, when prompted for mysql root user password, leave it blank i.e. Press Enter

$ cd /usr/local/src/kamailio/utils/kamctl/mysql
$ mysql -u root -p pcscf < standard-create.sql
$ mysql -u root -p pcscf < presence-create.sql
$ mysql -u root -p pcscf < ims_usrloc_pcscf-create.sql
$ mysql -u root -p pcscf < ims_dialog-create.sql

$ mysql -u root -p scscf < standard-create.sql
$ mysql -u root -p scscf < presence-create.sql
$ mysql -u root -p scscf < ims_usrloc_scscf-create.sql
$ mysql -u root -p scscf < ims_dialog-create.sql
$ mysql -u root -p scscf < ims_charging-create.sql

$ cd /usr/local/src/kamailio/misc/examples/ims/icscf
$ mysql -u root -p icscf < icscf.sql

Verify that following tables are present in respective databases by logging into mysql

+-----------------+
| Tables_in_pcscf |
+-----------------+
| active_watchers |
| dialog_in       |
| dialog_out      |
| dialog_vars     |
| location        |
| presentity      |
| pua             |
| version         |
| watchers        |
| xcap            |
+-----------------+

+-----------------+
| Tables_in_scscf |
+-----------------+
| active_watchers |
| contact         |
| dialog_in       |
| dialog_out      |
| dialog_vars     |
| impu            |
| impu_contact    |
| impu_subscriber |
| presentity      |
| pua             |
| ro_session      |
| subscriber      |
| version         |
| watchers        |
| xcap            |
+-----------------+

+---------------------+
| Tables_in_icscf     |
+---------------------+
| nds_trusted_domains |
| s_cscf              |
| s_cscf_capabilities |
+---------------------+

<mysql> grant delete,insert,select,update on pcscf.* to pcscf@localhost identified by 'heslo';
<mysql> grant delete,insert,select,update on scscf.* to scscf@localhost identified by 'heslo';
<mysql> grant delete,insert,select,update on icscf.* to icscf@localhost identified by 'heslo';
<mysql> grant delete,insert,select,update on icscf.* to provisioning@localhost identified by 'provi';
<mysql> GRANT ALL PRIVILEGES ON pcscf.* TO 'pcscf'@'%' identified by 'heslo';
<mysql> GRANT ALL PRIVILEGES ON scscf.* TO 'scscf'@'%' identified by 'heslo';
<mysql> GRANT ALL PRIVILEGES ON icscf.* TO 'icscf'@'%' identified by 'heslo';
<mysql> GRANT ALL PRIVILEGES ON icscf.* TO 'provisioning'@'%' identified by 'provi';
<mysql> FLUSH PRIVILEGES;

Then,

$ mysql
<mysql> use icscf;
<mysql> INSERT INTO `nds_trusted_domains` VALUES (1,'ims.mnc001.mcc001.3gppnetwork.org');
<mysql> INSERT INTO `s_cscf` VALUES (1,'First and only S-CSCF','sip:scscf.ims.mnc001.mcc001.3gppnetwork.org:6060');
<mysql> INSERT INTO `s_cscf_capabilities` VALUES (1,1,0),(2,1,1);

14. Copy pcscf, icscf and scscf configuration files to /etc folder and edit accordingly

$ cd ~ && git clone https://github.com/herlesupreeth/Kamailio_IMS_Config
$ cd Kamailio_IMS_Config
$ cp -r kamailio_icscf /etc
$ cp -r kamailio_pcscf /etc
$ cp -r kamailio_scscf /etc

15. Setup the DNS for resolving IMS and EPC components names

$ apt install -y bind9

Use the below example DNS Zone file to create a DNS Zone file into the bind folder and edit /etc/bind/named.conf.local and /etc/bind/named.conf.options accordingly:

$ cd /etc/bind

In the below example: Kamailio IMS & DNS server running at 10.4.128.21/172.24.15.30 (Floating IP) and PCRF also at 10.4.128.21/172.24.15.30 (Floating IP)

$ cat ims.mnc001.mcc001.3gppnetwork.org

$ORIGIN ims.mnc001.mcc001.3gppnetwork.org.
$TTL 1W
@                       1D IN SOA       localhost. root.localhost. (
                                        1               ; serial
                                        3H              ; refresh
                                        15M             ; retry
                                        1W              ; expiry
                                        1D )            ; minimum

                        1D IN NS        ns
ns                      1D IN A         10.4.128.21

pcscf                   1D IN A         10.4.128.21
_sip._udp.pcscf         1D SRV 0 0 5060 pcscf
_sip._tcp.pcscf         1D SRV 0 0 5060 pcscf

icscf                   1D IN A         10.4.128.21
_sip._udp               1D SRV 0 0 4060 icscf
_sip._tcp               1D SRV 0 0 4060 icscf

scscf                   1D IN A         10.4.128.21
_sip._udp.scscf         1D SRV 0 0 6060 scscf
_sip._tcp.scscf         1D SRV 0 0 6060 scscf

hss                     1D IN A         10.4.128.21

Create another DNS zone for resolving pcrf domain as follows:

$ cat epc.mnc001.mcc001.3gppnetwork.org

$ORIGIN epc.mnc001.mcc001.3gppnetwork.org.
$TTL 1W
@                       1D IN SOA       localhost. root.localhost. (
                                        1               ; serial
                                        3H              ; refresh
                                        15M             ; retry
                                        1W              ; expiry
                                        1D )            ; minimum

                        1D IN NS        epcns
epcns                   1D IN A         10.4.128.21

pcrf                    1D IN A         127.0.0.5

Edit /etc/bind/named.conf.local file as follows:

//
// Do any local configuration here
//

// Consider adding the 1918 zones here, if they are not used in your
// organization
//include "/etc/bind/zones.rfc1918";

zone "ims.mnc001.mcc001.3gppnetwork.org" {
        type master;
        file "/etc/bind/ims.mnc001.mcc001.3gppnetwork.org";
};

zone "epc.mnc001.mcc001.3gppnetwork.org" {
        type master;
        file "/etc/bind/epc.mnc001.mcc001.3gppnetwork.org";
};

Edit /etc/bind/named.conf.options file as follows:

options {
        directory "/var/cache/bind";

        // If there is a firewall between you and nameservers you want
        // to talk to, you may need to fix the firewall to allow multiple
        // ports to talk.  See http://www.kb.cert.org/vuls/id/800113

        // If your ISP provided one or more IP addresses for stable
        // nameservers, you probably want to use them as forwarders.
        // Uncomment the following block, and insert the addresses replacing
        // the all-0's placeholder.

        //forwarders {
        // Put here the IP address of other DNS server which could be used if name cannot be resolved with DNS server running in this machine (Optional)
        //10.4.128.2;
        //};

        //========================================================================
        // If BIND logs error messages about the root key being expired,
        // you will need to update your keys.  See https://www.isc.org/bind-keys
        //========================================================================
        dnssec-validation no;
        allow-query { any; };

        auth-nxdomain no;    # conform to RFC1035
        //listen-on-v6 { any; };
};

$ systemctl restart bind9

Then, test DNS resolution by adding following entries on top of all other entries in /etc/resolv.conf (make sure it persist across reboots)

search ims.mnc001.mcc001.3gppnetwork.org
nameserver 10.4.128.21

Finally, ping to ensure

$ ping pcscf
PING pcscf.ims.mnc001.mcc001.3gppnetwork.org (10.4.128.21) 56(84) bytes of data.
64 bytes from localhost (10.4.128.21): icmp_seq=1 ttl=64 time=0.017 ms
64 bytes from localhost (10.4.128.21): icmp_seq=2 ttl=64 time=0.041 ms

To make changes in /etc/resolv.conf be persistent across reboot edit the /etc/netplan/50-cloud-init.yaml file as follows:

# This file is generated from information provided by
# the datasource.  Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
    version: 2
    ethernets:
        ens3:
            dhcp4: true
            match:
                macaddress: fa:16:3e:99:f5:67
            set-name: ens3
            nameservers:
                search: [ims.mnc001.mcc001.3gppnetwork.org,epc.mnc001.mcc001.3gppnetwork.org]
                addresses:
                      - 10.4.128.21
    version: 2

$ netplan apply
$ ln -sf /run/systemd/resolve/resolv.conf /etc/resolv.conf
$ systemctl restart systemd-resolved.service

16. Install RTPEngine

Check for dependencies, install dependencies and build .deb packages

$ export DEB_BUILD_PROFILES="pkg.ngcp-rtpengine.nobcg729"
$ apt install dpkg-dev
$ git clone https://github.com/sipwise/rtpengine
$ cd rtpengine && git checkout mr7.4.1
$ dpkg-checkbuilddeps

The above command checks for dependencies and give you a list of dependencies which are missing in the system. The below list is the result of this command

$ apt install debhelper default-libmysqlclient-dev gperf iptables-dev libavcodec-dev libavfilter-dev libavformat-dev libavutil-dev libbencode-perl libcrypt-openssl-rsa-perl libcrypt-rijndael-perl libdigest-crc-perl libdigest-hmac-perl libevent-dev libhiredis-dev libio-multiplex-perl libio-socket-inet6-perl libiptc-dev libjson-glib-dev libnet-interface-perl libpcap0.8-dev libsocket6-perl libspandsp-dev libswresample-dev libsystemd-dev libxmlrpc-core-c3-dev markdown dkms module-assistant keyutils libnfsidmap2 libtirpc1 nfs-common rpcbind

After installing dependencies run the below command again and verify that no dependencies are left out

$ dpkg-checkbuilddeps

This should just return back to shell with no output if all depedencies are met

$ dpkg-buildpackage -uc -us
$ cd ..
$ dpkg -i *.deb
$ cp /etc/rtpengine/rtpengine.sample.conf /etc/rtpengine/rtpengine.conf

Edit this file as follows under [rtpengine]:

interface = 10.4.128.21

Port on which rtpengine binds i.e. listen_ng parameter is udp port 2223. This should be updated in kamailio_pcscf.cfg file at modparam(rtpengine …)

# ----- rtpproxy params -----
modparam("rtpengine", "rtpengine_sock", "1 == udp:localhost:2223")

Edit /etc/default/ngcp-rtpengine-daemon and /etc/default/ngcp-rtpengine-recording-daemon as follows in respective files:

RUN_RTPENGINE=yes

RUN_RTPENGINE_RECORDING=yes

$ cp /etc/rtpengine/rtpengine-recording.sample.conf /etc/rtpengine/rtpengine-recording.conf
$ mkdir /var/spool/rtpengine
$ systemctl restart ngcp-rtpengine-daemon.service ngcp-rtpengine-recording-daemon.service ngcp-rtpengine-recording-nfs-mount.service
$ systemctl enable ngcp-rtpengine-daemon.service ngcp-rtpengine-recording-daemon.service ngcp-rtpengine-recording-nfs-mount.service

$ systemctl stop rtpproxy
$ systemctl disable rtpproxy
$ systemctl mask rtpproxy

Second instance of RTPENGINE can be run as follows (Optional)

$ iptables -I rtpengine -p udp -j RTPENGINE --id 1
$ ip6tables -I INPUT -p udp -j RTPENGINE --id 1
$ echo 'del 1' > /proc/rtpengine/control
$ /usr/sbin/rtpengine --table=1 --interface=10.4.128.21 --listen-ng=127.0.0.1:2224 --tos=184 --pidfile=ngcp-rtpengine-daemon2.pid --no-fallback --foreground

17. Running I-CSCF, P-CSCF and S-CSCF as separate process

First, stop the default kamailio SIP server

$ systemctl stop kamailio
$ systemctl disable kamailio
$ systemctl mask kamailio

Run all the process as root and NOT sudo

$ mkdir -p /var/run/kamailio_pcscf
$ kamailio -f /etc/kamailio_pcscf/kamailio_pcscf.cfg -P /kamailio_pcscf.pid -DD -E -e

$ mkdir -p /var/run/kamailio_scscf
$ kamailio -f /etc/kamailio_scscf/kamailio_scscf.cfg -P /kamailio_scscf.pid -DD -E -e

$ mkdir -p /var/run/kamailio_icscf
$ kamailio -f /etc/kamailio_icscf/kamailio_icscf.cfg -P /kamailio_icscf.pid -DD -E -e

18. Install Open5GS in the same machine as Kamailio IMS – Install Open5GS from source

Please refer to instructions at https://open5gs.org/open5gs/docs/guide/02-building-open5gs-from-sources/

If you are using OpenStack, installing Open5GS and Kamailio IMS on the same machine is very important because the Framed-IP-Address in the AAR request via Rx interface takes received IP address and port in ims_qos module, hence, if the Open5GS is on a separate VM/machine, the IP and port received in received_ip and received_port values seen by Kamailio IMS will be the NATed IP of the Open5GS machine resulting in failing of AAR request.

Modify below mentioned parts of configuration files in addition to Configure Open5GS section. For reference, look at the configuration files at https://github.com/herlesupreeth/Open5gs_Config. These configuration only holds for open5gs tag v1.3.0, please tweak configuration files based on the open5gs tag you use.

  • Change realm of components to epc.mnc001.mcc001.3gppnetwork.org
  • Define IP pools for APNs used i.e one for default APN and another for IMS apn
  • Define P-CSCF address in the pgw configuration
  • Define a ConnectPeer for pcscf.ims.mnc001.mcc001.3gppnetwork.org with its IP and port in PCRF freediameter configuration
  • Setup IP tables for the UE pools defined and create appropriate tun interfaces

Below startup script can be used for setting up interfaces:

#!/bin/bash

sudo sysctl -w net.ipv4.ip_forward=1
sudo sysctl -w net.ipv6.conf.all.forwarding=1

ip tuntap add name ogstun mode tun
ip addr add 192.168.100.1/24 dev ogstun
ip addr add fd84:6aea:c36e:2b69::/48 dev ogstun
ip link set ogstun mtu 1400
ip link set ogstun up
iptables -t nat -A POSTROUTING -s 192.168.100.0/24 ! -o ogstun -j MASQUERADE
ip6tables -t nat -A POSTROUTING -s fd84:6aea:c36e:2b69::/48 ! -o ogstun -j MASQUERADE
iptables -I INPUT -i ogstun -j ACCEPT
ip6tables -I INPUT -i ogstun -j ACCEPT

ip tuntap add name ogstun2 mode tun
ip addr add 192.168.101.1/24 dev ogstun2
ip addr add fd1f:76f3:da9b:0101::/48 dev ogstun2
ip link set ogstun2 mtu 1400
ip link set ogstun2 up
iptables -t nat -A POSTROUTING -s 192.168.101.0/24 ! -o ogstun2 -j MASQUERADE
ip6tables -t nat -A POSTROUTING -s fd1f:76f3:da9b:0101::/48 ! -o ogstun2 -j MASQUERADE
iptables -I INPUT -i ogstun2 -j ACCEPT
ip6tables -I INPUT -i ogstun2 -j ACCEPT

ufw disable

Add users with following APN settings in Open5GS:

APN Configuration:
---------------------------------------------------------------------------------------------------------------------
| APN      | Type | QCI | ARP | Capability | Vulnerablility | MBR DL/UL(Kbps)     | GBR DL/UL(Kbps) | PGW IP        |
---------------------------------------------------------------------------------------------------------------------
| internet | IPv4 | 9   | 8   | Disabled   | Disabled       | unlimited/unlimited |                 |               |
---------------------------------------------------------------------------------------------------------------------
| ims      | IPv4 | 5   | 1   | Disabled   | Disabled       | 3850/1530           |                 |               |
|          |      | 1   | 2   | Enabled    | Enabled        | 128/128             | 128/128         |               |
|          |      | 2   | 4   | Enabled    | Enabled        | 128/128             | 128/128         |               |
---------------------------------------------------------------------------------------------------------------------

Finally, make sure of the following in Open5GS

  • PCO options which indicate the address of the Proxy-CSCF
  • Need to indicate support for Voice-over-Packet-Switched (VoPS) in NAS message to UE from EPC

19. Setup FoHSS in order to talk with I-CSCF and S-CSCF

Requirements for FoHSS: Install Java JDK and ant

Download Oracle Java 7 JDK from following link using a browser:

https://www.oracle.com/technetwork/java/javase/downloads/java-archive-downloads-javase7-521261.html

$ mkdir -p  /usr/lib/jvm/
$ tar -zxf jdk-7u79-linux-x64.tar.gz -C /usr/lib/jvm/
$ update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk1.7.0_79/bin/java 100
$ update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/jdk1.7.0_79/bin/javac 100

Verify that java has been successfully configured by running:

$ update-alternatives --display java
java - auto mode
  link best version is /usr/lib/jvm/jdk1.7.0_79/bin/java
  link currently points to /usr/lib/jvm/jdk1.7.0_79/bin/java
  link java is /usr/bin/java
/usr/lib/jvm/jdk1.7.0_79/bin/java - priority 100

$ update-alternatives --display javac
javac - auto mode
  link best version is /usr/lib/jvm/jdk1.7.0_79/bin/javac
  link currently points to /usr/lib/jvm/jdk1.7.0_79/bin/javac
  link javac is /usr/bin/javac
/usr/lib/jvm/jdk1.7.0_79/bin/javac - priority 100

$ update-alternatives --config java
(select java jdk1.7.0_79)
$ update-alternatives --config javac

Check java version

$ java -version
java version "1.7.0_79"
Java(TM) SE Runtime Environment (build 1.7.0_79-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)

Install Ant

$ cd ~
$ wget http://archive.apache.org/dist/ant/binaries/apache-ant-1.9.14-bin.tar.gz
$ tar xvfvz apache-ant-1.9.14-bin.tar.gz
$ mv apache-ant-1.9.14 /usr/local/
$ sh -c 'echo ANT_HOME=/usr/local/  >> /etc/environment'
$ ln -s /usr/local/apache-ant-1.9.14/bin/ant /usr/bin/ant

Verfiy ant version as follows:

$ ant -version
Apache Ant(TM) version 1.9.14 compiled on March 12 2019

Create working directories for OpenIMSCore:

$ mkdir /opt/OpenIMSCore
$ cd /opt/OpenIMSCore

Download:

$ git clone https://github.com/herlesupreeth/FHoSS

Compile:

$ cd FHoSS
$ export JAVA_HOME="/usr/lib/jvm/jdk1.7.0_79"
$ export CLASSPATH="/usr/lib/jvm/jdk1.7.0_79/jre/lib/"
$ ant compile deploy | tee ant_compile_deploy.txt

Create configurator.sh using below script to change domain names and IP address in all configuration files

$ cd deploy
$ vim configurator.sh

#!/bin/bash

# Initialization & global vars
# if you execute this script for the second time
# you should change these variables to the latest
# domain name and ip address
DDOMAIN="open-ims\.test"
DSDOMAIN="open-ims\\\.test"
DEFAULTIP="127\.0\.0\.1"
CONFFILES=`ls *.cfg *.xml *.sql *.properties 2>/dev/null`

# Interaction
printf "Domain Name:"
read domainname 
printf "IP Adress:"
read ip_address

# input domain is to be slashed for cfg regexes 
slasheddomain=`echo $domainname | sed 's/\./\\\\\\\\\./g'`

  if [ $# != 0 ] 
  then 
  printf "changing: "
      for j in $* 
      do
    sed -i -e "s/$DDOMAIN/$domainname/g" $j
    sed -i -e "s/$DSDOMAIN/$slasheddomain/g" $j
    sed -i -e "s/$DEFAULTIP/$ip_address/g" $j
    printf "$j " 
      done
  echo 
  else 
  printf "File to change [\"all\" for everything, \"exit\" to quit]:"
  # loop
      while read filename ;
      do
        if [ "$filename" = "exit" ] 
        then 
        printf "exitting...\n"
        break ;

      elif [ "$filename" = "all" ]
      then    
          printf "changing: "
         for i in $CONFFILES 
         do
        sed -i -e "s/$DDOMAIN/$domainname/g" $i
        sed -i -e "s/$DSDOMAIN/$slasheddomain/g" $i
        sed -i -e "s/$DEFAULTIP/$ip_address/g" $i
        
        printf "$i " 
         done 
         echo 
         break;

        elif [ -w $filename ] 
        then
            printf "changing $filename \n"
            sed -i -e "s/$DDOMAIN/$domainname/g" $filename
            sed -i -e "s/$DSDOMAIN/$slasheddomain/g" $filename
            sed -i -e "s/$DEFAULTIP/$ip_address/g" $filename

          else 
          printf "cannot access file $filename. skipping... \n" 
        fi
        printf "File to Change:"
      done 
  fi

$ chmod +x configurator.sh
$ ./configurator.sh 
Domain Name:ims.mnc001.mcc001.3gppnetwork.org
IP Adress:10.4.128.21

$ grep -r "open-ims"
(Change realm name in the below file from open-ims.test to ims.mnc001.mcc001.3gppnetwork.org)
$ vim webapps/hss.web.console/WEB-INF/web.xml
$ vim hibernate.properties

And, change the following line:

hibernate.connection.url=jdbc:mysql://127.0.0.1:3306/hss_db

$ cp configurator.sh ../scripts/
$ cd ../scripts
$ grep -r "open-ims"
$ ./configurator.sh 
Domain Name:ims.mnc001.mcc001.3gppnetwork.org
IP Adress:10.4.128.21

$ cp configurator.sh ../config/
$ cd ../config
$ ./configurator.sh 
Domain Name:ims.mnc001.mcc001.3gppnetwork.org
IP Adress:10.4.128.21

$ cd ../src-web
$ vim WEB-INF/web.xml

And, change open-ims.test to ims.mnc001.mcc001.3gppnetwork.org

Prepare mysql database:

$ mysql
<mysql> drop database hss_db;
<mysql> create database hss_db;
<mysql> quit

Import database located at /opt/OpenIMSCore into hss_db

$ cd /opt/OpenIMSCore
$ mysql -u root -p hss_db < FHoSS/scripts/hss_db.sql
$ mysql -u root -p hss_db < FHoSS/scripts/userdata.sql

Check grants for mysql access rights at first time installation:

$ mysql
# See last line in hss_db.sql:
<mysql> grant delete,insert,select,update on hss_db.* to hss@localhost identified by 'hss';
<mysql> grant delete,insert,select,update on hss_db.* to hss@'%' identified by 'hss';

Check database if domain names are o.k. in various entries and privileges

$ mysql -u hss -p
<mysql> show databases;
<mysql> use hss_db;
<mysql> select * from impu;

Prepare script-file, start HSS

Copy startup.sh to hss.sh in root directory

$ cp /opt/OpenIMSCore/FHoSS/deploy/startup.sh /root/hss.sh

And, add the following to hss.sh before echo Building Classpath

cd /opt/OpenIMSCore/FHoSS/deploy
JAVA_HOME="/usr/lib/jvm/jdk1.7.0_79"
CLASSPATH="/usr/lib/jvm/jdk1.7.0_79/jre/lib/"

Start HSS using hss.sh

$ ./hss.sh

Access the web-interface of HSS: http://<IMS_VM_FLOATING_IP>:8080/hss.web.console/

For example, http://172.24.15.30:8080/hss.web.console/

user:      hssAdmin
password:  hss

Then, edit the /etc/hosts file as follows:

In the below example. epc-ims is the hostname of the machine

root@epc-ims:~# cat /etc/hosts
127.0.0.1    localhost
127.0.0.1    epc-ims

20. Add IMS subscription use in FoHSS as follows from the Web GUI

Assuming IMSI of the user as 001010123456791 and MSISDN is 0198765432100

Login to the HSS web console.
Navigate to the User Identities page
Create the IMSU 
Click IMS Subscription / Create
Enter:
Name = 001010123456791
Capabilities Set = cap_set1
Preferred S-CSCF = scsf1
Click Save

Create the IMPI and Associate the IMPI to the IMSU
Click Create & Bind new IMPI
Enter:
Identity = 001010123456791@ims.mnc001.mcc001.3gppnetwork.org
Secret Key = 8baf473f2f8fd09487cccbd7097c6862 (Ki value as in Open5GS HSS database)
Authentication Schemes - All
Default = Digest-AKAv1-MD5
AMF = 8000 (As in Open5GS HSS database)
OP = 11111111111111111111111111111111 (As in Open5GS HSS database)
SQN = 000000021090 (SQN value as in Open5GS HSS database)
Click Save

Create and Associate IMPI to IMPU
Click Create & Bind new IMPU
Enter:
Identity = sip:001010123456791@ims.mnc001.mcc001.3gppnetwork.org
Barring = Yes
Service Profile = default_sp
Charging-Info Set = default_charging_set
IMPU Type = Public_User_Identity
Click Save

Add Visited Network to IMPU
Enter:
Visited Network = ims.mnc001.mcc001.3gppnetwork.org
Click Add

Now, goto Public User Identity and create further IMPUs as following

1. tel:0198765432100

Public User Identity -IMPU-
Identity = tel:0198765432100
Service Profile = default_sp
Charging-Info Set = default_charging_set
Can Register = Yes
IMPU Type = Public_User_Identity
Click Save

Add Visited Network to IMPU
Enter:
Visited Network = ims.mnc001.mcc001.3gppnetwork.org
Click Add

Associate IMPI(s) to IMPU
IMPI Identity = 001010123456791@ims.mnc001.mcc001.3gppnetwork.org
Click Add

2. sip:0198765432100@ims.mnc001.mcc001.3gppnetwork.org

Public User Identity -IMPU-
Identity = sip:0198765432100@ims.mnc001.mcc001.3gppnetwork.org
Service Profile = default_sp
Charging-Info Set = default_charging_set
Can Register = Yes
IMPU Type = Public_User_Identity
Click Save

Add Visited Network to IMPU
Enter:
Visited Network = ims.mnc001.mcc001.3gppnetwork.org
Click Add

Associate IMPI(s) to IMPU
IMPI Identity = 001010123456791@ims.mnc001.mcc001.3gppnetwork.org
Click Add

And, finally add these IMPUs as implicit set of IMSI derived IMPU in HSS i.e sip:001010123456791@ims.mnc001.mcc001.3gppnetwork.org as follows:

1. Goto to IMPU sip:001010123456791@ims.mnc001.mcc001.3gppnetwork.org
2. In "Add IMPU(s) to Implicit-Set" section give IMPU Identity created above to be added to this IMPU

21. APN settings

Clear all previous APN settings

Then, create APN as follows:

  • First create internet APN, APN name: internet, APN type: default –> Save APN
  • Then, create ims APN, APN name: ims, APN type: ims –> Save APN

22. eNB settings

Must have in the eNB:

  • Support for QoS
  • Support for Dedicated radio bearer creation
  • Make sure to check the DRB configuration with respect to QCI of APN accordingly (QCI 5 for ims)

On the eNB machine have the following static routes (since internal IP of the VM is advertised in S1AP messages and UE wont find the core in Uplink)

$ ip r add 10.4.128.21/32 via 172.24.15.30

23. USIM and UE settings

24. Start IMS components and FoHSS followed by Open5GS and eNB, then try connecting the phones

25. Test voice call

Assuming IMSI of the user1 as 001010123456791 and MSISDN is 0198765432100 and IMSI of the user2 as 001010123456792 and MSISDN is 0298765432100. Try calling user2 from user1 by dialing its MSISDN ie. 0298765432100

26. For debugging

Debug using wireshark at Open5GS machine and following wireshark display filter

s1ap || gtpv2 || pfcp || diameter || diameter.3gpp || sip

Also,

Debugging Diameter messages between PCRF and P-CSCF in Wireshark if the TCP/SCTP port other than 3868

Open Wireshark –> Preferences –> Protocols –> Diameter –> Change to whatever ports are being used

Appendix

Open5GS

Open5GS is a C-language implementation of 5G Core and EPC, i.e. the core network of NR/LTE network (Release-17)