[SR-Users] IMS: SMS over IP - how to get the originator's tel address?

Wed Nov 21 20:59:42 CET 2018

Carsten – thanks for the reply.

I am not trying to change it – the tel identity (and other public identities) is already defined in the profile stored in the HSS; I want the S-CSCF to insert P-Preferred-Identity headers for the IMPU’s associated with the UE, which it already knows since it downloaded the profile directly from the HSS.

The P-CSCF and the handset itself may know these public identities as well if it would have SUBSCRIBEd for registration events from the S-CSCF, but in practice, I do not see the handset providing anything other than the IMPI, and the Kamailio-based P-CSCF with my current configuration does not insert any P-Asserted-Identity headers.

TS 24.341 does suggest that either the P-CSCF or the S-CSCF could insert the header(s), and in the examples provided in Annex B.5 of the same document show the additional P-Asserted-Identity header being added by the S-CSCF before forwarding the request to the IP-SM-GW:

UE to P-CSCF

MESSAGE sip:sc.home1.net SIP/2.0

Via: SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp; branch=z9hG4bKnashds7

Max-Forwards: 70

Route: <sip:pcscf1.visited1.net:7531;lr;comp=sigcomp>, <sip:orig at scscf1.home1.net;lr>

P-Preferred-Identity: "John Doe" <sip:user1_public1 at home1.net>

From: <sip:user1_public1 at home1.net>; tag=171828

To: <sip:sc.home1.net.net>

Call-ID: cb03a0s09a2sdfglkj490333

Cseq: 666 MESSAGE

Content-Type: application/vnd.3gpp.sms 

Content-Length: (...)

P-CSCF to S-CSCF

MESSAGE sip:sc.home1.net SIP/2.0

Via: SIP/2.0/UDP pcscf1.visited1.net;branch=z9hG4bK240f341, SIP/2.0/UDP

[5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp; branch=z9hG4bKnashds7

Max-Forwards: 69

Route: <sip:orig at scscf1.home1.net;lr>

P-Asserted-Identity: "John Doe" <sip:user1_public1 at home1.net>

From: <sip:user1_public1 at home1.net>; tag=171828

To: <sip:sc.home1.net>

Call-ID: cb03a0s09a2sdfglkj490333

Cseq: 666 MESSAGE

Content-Type: application/vnd.3gpp.sms

Content-Length: (...)

S-CSCF to IP-SM-GW

MESSAGE sip:sc.home1.net SIP/2.0

Via: SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bK344a651, SIP/2.0/UDP

pcscf1.visited1.net;branch=z9hG4bK240f341, SIP/2.0/UDP

[5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp; branch=z9hG4bKnashds7

Max-Forwards: 68

Route: <sip:ipsmgw.home1.net;lr>, <sip:cb03a0s09a2sdfglkj490333 at scscf1.home1.net;lr>

P-Asserted-Identity: "John Doe" <sip:user1_public1 at home1.net>

P-Asserted-Identity: tel:+12125551111

From: <sip:user1_public1 at home1.net>; tag=171828

To: <sip:sc.home1.net>

Call-ID: cb03a0s09a2sdfglkj490333

Cseq: 666 MESSAGE

Content-Type: application/vnd.3gpp.sms

Content-Length: (...)

Ron

From: sr-users [mailto:sr-users-bounces at lists.kamailio.org] On Behalf Of Carsten Bock
Sent: Wednesday, November 21, 2018 12:35 AM
To: Kamailio (SER) - Users Mailing List
Subject: Re: [SR-Users] IMS: SMS over IP - how to get the originator's tel address?

Hi Ron,

You can't change it on the Proxy-CSCF, but on the HSS. According to 3GPP Specs, the first identity associated to an IMPI is the "default-identity", which is typically used by the phone and asserted by the Proxy-CSCF.

Thanks,

Carsten

Am Mi., 21. Nov. 2018, 00:31 hat Ron McLeod <ron.kamailio at mcleodnet.com> geschrieben:

I am working on a VoLTE/IMS scenario to transfer text messages as SMS over IP (+g.3gpp.smsip feature) between UE’s.  This is a high-level view of the message flows between the endpoints (not showing CSCFs):

UE1                                 IP-SM-GW

|---- MESSAGE (SUBMIT) --------------->|

|<------------------- 202 ACCEPTED ----|

|                                      | 

 |<-------- MESSAGE (SUBMIT_REPORT) ----|

|---- 200 OK ------------------------->|

                                        |  

UE2                                     |

|                                      |  

 |<-------------- MESSAGE (DELIVER) ----|

|---- 200 OK ------------------------->|

The messages does get transferred from UE1 to UE2 successfully.  Since this is GSM-style SMS, the OA (originating address) and DA (destination address) are specified using telephone numbers, not sip addresses.  This is not a problem for the DA, since it is specified in the SUBMIT TPDU from the originating handset, but when the IP-SM-GW sends the DELIVER TPDU it needs to specify the OA so that the recipient knows who sent the SMS, and this was not provided in the MESSAGE with the SMS-SUBMIT.

According to 3GPP TS 24.341 (http://www.qtc.jp/3GPP/Specs/24341-b20.pdf):

"The IP-SM-GW will have to use an address of the SM-over-IP sender that the SC can process (i.e. an E.164 number).  This address will come from a tel URI in a P-Asserted-Identity header (as defined in RFC 3325 [13]) placed in the SIP MESSAGE request by the P-CSCF or S-CSCF."

Looking at the MESSAGE request sent from the S-CSCF to the IP-SM-GW, it looks like neither the P-CSCF nor the S-CSCF is providing the tel address in a P-Asserted-Identity header:

MESSAGE tel:+3108012345680 SIP/2.0

Route: <sip:defaultapp at tas.core.ims1.test;lr>, <sip:iscmark at scscf.core.ims1.test:6060;lr;s=1;h=0;d=0;a=7369703a30303130333031323334353637383940696d732e6d6e633030332e6d63633030312e336770706e6574776f726b2e6f7267>

P-Served-User: <sip:001030123456789 at ims.mnc003.mcc001.3gppnetwork.org <mailto:sip%3A001030123456789 at ims.mnc003.mcc001.3gppnetwork.org> >;sescase=orig;regstate=reg

f: <sip:001030123456789 at ims.mnc003.mcc001.3gppnetwork.org <mailto:sip%3A001030123456789 at ims.mnc003.mcc001.3gppnetwork.org> >;tag=2703358633

t: <tel:+3108012345680>

CSeq: 555874977 MESSAGE

i: 2703358625_2324045032 at 2001:470:eb88:b021:27f:9507:589d:c201

Via: SIP/2.0/UDP [2001:470:EB88:150:0:0:0:22]:6060;branch=z9hG4bKb857.bd3345ba81ec10b1d11639d9c7414606.0;i=a

Via: SIP/2.0/TCP [2001:470:EB88:150:5054:FF:FE44:BFC9];branch=z9hG4bKb857.be53cc1c583b9c5f9dcebf3306f2b7c1.0

v: SIP/2.0/UDP [2001:470:eb88:b021:27f:9507:589d:c201]:8906;rport=8013;branch=z9hG4bK3552622488

Max-Forwards: 68

P-Access-Network-Info: 3GPP-E-UTRAN-FDD; utran-cell-id-3gpp=0010300030000001

c: application/vnd.3gpp.sms

Allow: MESSAGE

d: no-fork

User-Agent: Xiaomi_Redmi 3S_Android6.0.1_9

l: 27

P-Charging-Vector: icid-value=49565300000000511100004B01000000; icid-generated-at=2001:470:EB88:150:5054:FF:FE44:BFC9

P-Asserted-Identity: <sip:001030123456789 at ims.mnc003.mcc001.3gppnetwork.org <mailto:sip%3A001030123456789 at ims.mnc003.mcc001.3gppnetwork.org> >

P-Visited-Network-ID: core.ims1.test

Message Body

    GSM A-I/F RP - RP-DATA (MS to Network)

        Message Type RP-DATA (MS to Network)

        RP-Message Reference

            RP-Message Reference: 0x05 (5)

        RP-Originator Address

        RP-Destination Address - (3108012345680)

        RP-User Data

            Length: 14

            TPDU (not displayed)

     GSM SMS TPDU (GSM 03.40) SMS-SUBMIT

           0... .... = TP-RP: TP Reply Path parameter is not set in this SMS SUBMIT/DELIVER

           .0.. .... = TP-UDHI: The TP UD field contains only the short message

           ..1. .... = TP-SRR: A status report is requested

           ...0 0... = TP-VPF: TP-VP field not present (0)

           .... .0.. = TP-RD: Instruct SC to accept duplicates

           .... ..01 = TP-MTI: SMS-SUBMIT (1)

           TP-MR: 92

           TP-Destination-Address - (8000)

           TP-PID: 0

           TP-DCS: 0

           TP-User-Data-Length: (5) depends on Data-Coding-Scheme

           TP-User-Data

                SMS text: HELLO

Is this something that in configurable at the P-CSCF or the S-CSCF, or would it require now development?

Thanks,

Ron

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