How to enable roaming in IMS platform using the HSS web GUI

When you try to register IMS user via P-CSCF in visited network (roaming) in Kamailio IMS platform you will probably get following error:

403 Forbidden - HSS Roaming not allowed

This means that user is not allowed to register to appropriate IMS domain. So you will need to allow user in HSS databaze to use this visited network.

Our domain is ims3.sip.uniza.sk and we want to register user sip:student@ims3.sip.uniza.sk via P-CSCF in domain ims1.sip.uniza.sk (pcscf.ims1.sip.uniza.sk):

Adding new visited network

At first we need to add Visited network.

Navigate in HSS Choose Network configuration from upper menu,

from left menu under Visited Networks choose Create and then insert Indentity (domain name of visited network), then click on Save.

To verify successful creation you can Search (then click on Search) in Visited Networks:

Assign visited network to user

Then you will need to assign created visited network to user (his public user identity sip:student@ims3.sip.uniza.sk)

Choose User identities from upper menu,

navigate to the left menu and under Public User Identity choose Search and select appropriate user.

Add visited network (ims1.sip.uniza.sk in our case). Without this user is not allowed to register to IMS domain ims1.sip.uniza.sk.

After adding it appears under List of Visited Networks:

After these steps we are able to register with user sip:student@ims3.sip.uniza.sk in ims1.sip.uniza.sk domain.

Testing

We tested registration of sip:student@ims3.sip.uniza.sk on Monster IMS client ver. 0.9.25.

We set the PCSCF address for pcscf.ims1.sip.uniza.sk as on the following picture:

Here is captured registration flow (158.193.139.40 is IP address of pcscf.ims1.sip.uniza.sk):

UDP 172.16.1.99:5060 --> 158.193.139.40:5060
REGISTER sip:ims3.sip.uniza.sk SIP/2.0
Call-ID: d0e1e82b6102d00f0f1e21178aa43d26@172.16.1.99
CSeq: 1 REGISTER
From: "student" <sip:student@ims3.sip.uniza.sk>;tag=1000
To: "student" <sip:student@ims3.sip.uniza.sk>
Via: SIP/2.0/UDP 172.16.1.99:5060;branch=z9hG4bK787ce1057018bd12f33c3aa672de8eac34
Max-Forwards: 20
Expires: 3600
Authorization: Digest username="student@ims3.sip.uniza.sk",realm="ims3.sip.uniza.sk",nonce="",response="",uri="sip:ims3.sip.uniza.sk"
Contact: "student" <sip:student@172.16.1.99:5060>;+sip.instance=76a5671b-9b2d-4f1a-8f87-a24ca4d0f0ae
User-Agent: monster Version: 0.9.25
Content-Length: 0

UDP 158.193.139.40:5060 --> 172.16.1.99:5060
SIP/2.0 401 Unauthorized - Challenging the UE
Call-ID: d0e1e82b6102d00f0f1e21178aa43d26@172.16.1.99
CSeq: 1 REGISTER
From: "student" <sip:student@ims3.sip.uniza.sk>;tag=1000
To: "student" <sip:student@ims3.sip.uniza.sk>;tag=68988887aea29c51493f22b8b0542a94-eddd
Via: SIP/2.0/UDP 172.16.1.99:5060;rport=2423;received=158.193.139.247;branch=z9hG4bK787ce1057018bd12f33c3aa672de8eac34
Path: <sip:term@pcscf.ims1.sip.uniza.sk:5060;lr>
Service-Route: <sip:orig@scscf2.ims3.sip.uniza.sk:5060;lr>
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, PUBLISH, MESSAGE, INFO
Server: Serving-CSCF
Content-Length: 0
WWW-Authenticate: Digest realm="ims3.sip.uniza.sk", nonce="be5cc05c338e1673f621c3785e3ca810", algorithm=MD5, qop="auth,auth-int"

UDP 172.16.1.99:5060 --> 158.193.139.40:5060
REGISTER sip:ims3.sip.uniza.sk SIP/2.0
Call-ID: d0e1e82b6102d00f0f1e21178aa43d26@172.16.1.99
CSeq: 2 REGISTER
From: "student" <sip:student@ims3.sip.uniza.sk>;tag=1001
To: "student" <sip:student@ims3.sip.uniza.sk>
Via: SIP/2.0/UDP 172.16.1.99:5060;branch=z9hG4bKdd0043eb7e69a289c57c2fed244d7de634
Max-Forwards: 20
Authorization: Digest username="student@ims3.sip.uniza.sk",realm="ims3.sip.uniza.sk",nonce="be5cc05c338e1673f621c3785e3ca810",uri="sip:ims3.sip.uniza.sk",algoritm=MD5,response="a0784400bcbd4fe5f3abd5e73b174dc0",qop=auth-int,nc=00000001,cnonce="100561019853535198"
Expires: 3600
Contact: "student" <sip:student@172.16.1.99:5060>;+sip.instance=76a5671b-9b2d-4f1a-8f87-a24ca4d0f0ae
User-Agent: monster Version: 0.9.25
Content-Length: 0

UDP 158.193.139.40:5060 --> 172.16.1.99:5060
SIP/2.0 200 OK - SAR succesful and registrar saved
Call-ID: d0e1e82b6102d00f0f1e21178aa43d26@172.16.1.99
CSeq: 2 REGISTER
From: "student" <sip:student@ims3.sip.uniza.sk>;tag=1001
To: "student" <sip:student@ims3.sip.uniza.sk>;tag=68988887aea29c51493f22b8b0542a94-5359
Via: SIP/2.0/UDP 172.16.1.99:5060;rport=2423;received=158.193.139.247;branch=z9hG4bKdd0043eb7e69a289c57c2fed244d7de634
P-Associated-URI: <sip:student@ims3.sip.uniza.sk>
Contact: <sip:student@172.16.1.99:5060>;expires=3600;pub-gruu="sip:student@ims3.sip.uniza.sk;gr=76a5671b-9b2d-4f1a-8f87-a24ca4d0f0ae"
Path: <sip:term@pcscf.ims1.sip.uniza.sk:5060;lr>
Service-Route: <sip:orig@scscf2.ims3.sip.uniza.sk:5060;lr>
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, PUBLISH, MESSAGE, INFO
Server: Serving-CSCF
Content-Length: 0

You can see terminating P-CSCF address in Path header and serving S-CSCF in Service-Route header.

Both of them are in different domain, that means user student is in roaming.